1. A face matching device for matching (i) a target face image, included in a captured image and serving as a matching target, with (ii) a reference face image, registered in a reference image database and serving as a face image for reference, the reference image database being capable of (i) storing a plurality of reference face images for each registered person and further (ii) storing (a) for each of the plurality of reference face images, a reference face image capturing time, which is a time of capturing said each of the plurality of reference face images, and (b) a reference image age, which is an age of the registered person at the reference face image capturing time, the face matching device comprising: obtaining means for obtaining a target face image capturing time, which is a time of capturing the target face image; selecting means for selecting the reference face image for use in the matching on a basis of (i) the target face image capturing time obtained by the obtaining means and (ii) the reference face image capturing time stored in the reference image database; a coefficient storage section which stores a coefficient corresponding to a general age of the registered person, the coefficient (i) being at a maximum in a case where the general age is 0, (ii) decreasing as the general age increases, and (iii) changing at a rate which is higher as the general age is earlier; target image age determining means for determining, on a basis of (i) the target face image capturing time obtained by the obtaining means and (ii) the reference face image capturing time and the reference image age both stored in the reference image database, a target image age, which is an age of the registered person at the time of capturing the target face image; and applicability determining means for determining, by multiplying (i) a difference between the target face image capturing time obtained by the obtaining means and the reference face image capturing time stored in the reference image database by (ii) a value of the coefficient stored in the coefficient storage section which value corresponds to the target image age determined by the target image age determining means, an applicability indicative of how suitably said each of the plurality of reference face images is applicable in the matching with the target face image included in the captured image, the reference face image selected by the selecting means having an applicability, determined by the applicability determining means, which exceeds a predetermined threshold.