user5315: Sometimes we do thing intentionally sometimes unintentionally. But is there such thing such as unconscious intention in Buddhism (Theravada)? 

user111: No such thing! Consciousness(Vinnana) is present in all Vedana, Sanna, Sankhara. Intention falls under Sankhara.

user715: We may be fooled into thinking there is unconscious intention, because we are ignorant in some moments of the nature of dependant arising of that moment, but in reality every moment is conditional arising, and intention is a component of such arising.
If we were to observe deeply every moment in life, and trace the origins of every thought and impulse, it will firmly convince us from our own experience that this is how it works at all times. Of course, initially this may only be possible on a retreat or while in meditation.
The Dhammapada begins by stating this, 

Manopubbangama dhamma1
  manosettha manomaya manasa ce padutthena2
  bhasati va karoti va
  tato nam dukkhamanveti cakkamva vahato padam.
Verse 1: All mental phenomena have mind as their forerunner; they have
  mind as their chief; they are mind-made. If one speaks or acts with an
  evil mind, 'dukkha'3 follows him just as the wheel follows the
  hoofprint of the ox that draws the cart.

manopubbangama dhamma: All mental phenomena have Mind as their forerunner in the sense that Mind is the most dominant, and it is the
  cause of the other three mental phenomena, namely, Feeling (vedana),
  Perception (sanna) and Mental Formations or Mental Concomitants
  (sankhara). These three have Mind or Consciousness (vinnana) as their
  forerunner, because although they arise simultaneously with Mind they
  cannot arise if Mind does not arise. (The Commentary)
manasa ce padutthena (Verse 1) and manasi ce pasannena (Verse 2): Manasa here means intention or volition (cetana); volition leads one
  to the performance of volitional actions, both good and evil. This
  volition and the resultant actions constitute kamma; and kamma always
  follows one to produce results. Cakkhupala's blindness (Verse 1) was
  the consequence of his having acted with an evil intention in a
  previous existence and Matthakundali's happy existence in Tavatimsa
  celestial world (Verse 2) was the result of his mental devotion
  (manopasada) to the Buddha.
dukkha: In this context, dukkha mens suffering, or physical or mental pain, misfortune, unsatisfactoriness, evil consequences, etc.,
  and rebirth in the lower planes of existence or in the lower strata of
  human society if born in the human world.



5315: <p>Sometimes we do thing intentionally sometimes unintentionally. But is there such thing such as unconscious intention in Buddhism (Theravada)? </p>
 111: <p>No such thing! Consciousness(<a href="http://www.beyondthenet.net/dhamma/consciousness.htm" rel="nofollow">Vinnana</a>) is present in all <a href="http://www.beyondthenet.net/dhamma/feelings.htm" rel="nofollow">Vedana</a>, <a href="http://www.beyondthenet.net/dhamma/perceptions.htm" rel="nofollow">Sanna</a>, <a href="http://www.beyondthenet.net/dhamma/formations.htm" rel="nofollow">Sankhara</a>. Intention falls under Sankhara.</p>
 715: <p>We may be fooled into thinking there is unconscious intention, because we are ignorant in some moments of the nature of dependant arising of that moment, but in reality every moment is conditional arising, and intention is a component of such arising.</p>

<p>If we were to observe deeply every moment in life, and trace the origins of every thought and impulse, it will firmly convince us from our own experience that this is how it works at all times. Of course, initially this may only be possible on a retreat or while in meditation.</p>

<p>The Dhammapada <a href="http://www.tipitaka.net/tipitaka/dhp/verseload.php?verse=001" rel="nofollow">begins</a> by stating this, </p>

<blockquote>
  <p><em>Manopubbangama dhamma<sup>1</sup><br>
  manosettha manomaya manasa ce padutthena<sup>2</sup><br>
  bhasati va karoti va<br>
  tato nam dukkhamanveti cakkamva vahato padam.</em></p>
  
  <p>Verse 1: All mental phenomena have mind as their forerunner; they have
  mind as their chief; they are mind-made. If one speaks or acts with an
  evil mind, 'dukkha'<sup>3</sup> follows him just as the wheel follows the
  hoofprint of the ox that draws the cart.</p>
  
  <ol>
  <li><p><em>manopubbangama dhamma</em>: All mental phenomena have Mind as their forerunner in the sense that Mind is the most dominant, and it is the
  cause of the other three mental phenomena, namely, Feeling (vedana),
  Perception (sanna) and Mental Formations or Mental Concomitants
  (sankhara). These three have Mind or Consciousness (vinnana) as their
  forerunner, because although they arise simultaneously with Mind they
  cannot arise if Mind does not arise. (The Commentary)</p></li>
  <li><p><em>manasa ce padutthena (Verse 1) and manasi ce pasannena (Verse 2)</em>: Manasa here means intention or volition (cetana); volition leads one
  to the performance of volitional actions, both good and evil. This
  volition and the resultant actions constitute kamma; and kamma always
  follows one to produce results. Cakkhupala's blindness (Verse 1) was
  the consequence of his having acted with an evil intention in a
  previous existence and Matthakundali's happy existence in Tavatimsa
  celestial world (Verse 2) was the result of his mental devotion
  (manopasada) to the Buddha.</p></li>
  <li><p><em>dukkha</em>: In this context, dukkha mens suffering, or physical or mental pain, misfortune, unsatisfactoriness, evil consequences, etc.,
  and rebirth in the lower planes of existence or in the lower strata of
  human society if born in the human world.</p></li>
  </ol>
</blockquote>
