1. A transcranial magnetic stimulation apparatus for applying magnetic stimulation to a specific portion within a patient's head using a magnetic-field generation means disposed outside the head, the apparatus comprising: the magnetic-field generation means which is capable of moving toward a predetermined treatment irradiation position and posture thereof according to an operation of the patient or a patient assistant; a storage means which stores a three-dimensional MRI image of a patient's head that has been previously taken; a three-dimensional appearance image generation means which generates a three-dimensional appearance image of the patient's head in an initial posture; an image generation means which performs positional alignment between the three-dimensional MRI image and the three-dimensional appearance image, and generates a three-dimensional image of the patient's head after the positional alignment; a means which stores patterns of face characteristics as templates of characteristic regions, the face characteristics being suitable for tracking and being characteristics in the generated three-dimensional appearance image of the patient's head in the initial posture; an after-movement image generation means which generates, when the patient's head has been moved, a three-dimensional image of the patient's head after the movement; a means which finds out characteristic points in a face image after the movement using the templates to obtain three-dimensional coordinates of the characteristic regions; a means which detects changes of the posture from the initial posture using the characteristic regions in the face image in the initial posture and the characteristic regions in the face image after the movement; a magnetic-field generation means image generation means which generates an image of the magnetic-field generation means that indicates a current position of the magnetic-field generation means operated so as to maintain a positional relation with a specific portion on the three-dimensional MRI image of the patient's head; a display means which displays the three-dimensional image of the patient's head after the movement and the image of the magnetic-field generation means in one image; and a means which stores position and posture information about the predetermined treatment irradiation position and posture of the magnetic-field generating means as target information, in relation to the three-dimensional image of the patient's head after the movement, wherein the predetermined treatment irradiation position and posture of the magnetic-field generating means is indicated as a target on the display means, and wherein the means which stores patterns of face characteristics as templates of characteristic regions is configured to store the patterns of face characteristics as templates of characteristic regions without using any laser projectors.