In order to have a simplified structure, prevent a large size, and sufficiently widen an angle of view, the imaging device (1) according to the present invention is provided with an image forming optical system (2), and an imaging element (3) which takes a parallax image. The image forming optical system (2) is provided with a first negative lens group (4), a first positive lens group (5), and a second positive lens group (6). The first positive lens group (5) and the first negative lens group (4) are arranged along a common center axis. The second positive lens group (6) includes two positive lens groups (12, 13) arranged side by side in a parallax direction and across the common center axis, and each having a center axis, and is provided with two brightness stops (17) having respective openings arranged side by side in the parallax direction and across the common center axis so as to correspond to respective parallax images. The first negative lens group (4) includes, at the side closest to an object, a lens component having negative refractive power. The first positive lens group (5) has only one moving lens group (9) which moves along the common center axis during focusing. All the lens components of the image forming optical system (2) other than the moving lens group (9) remain stationary.Afin davoir une structure simplifiée, de ne pas être trop grand, et délargir suffisamment un angle de prise de vues, le dispositif imageur (1) selon la présente invention comprend un système optique de formation dimage (2), ainsi quun élément dimagerie (3) qui capture une image de parallaxe. Le système optique de formation dimage (2) est pourvu dun premier groupe de lentilles négatives (4), dun premier groupe de lentilles positives (5), et dun second groupe de lentilles positives (6). Le premier groupe de lentilles positives (5) et le premier groupe de lentilles négatives (4) sont disposés le long dun axe central commun. Le second groupe de lentilles positives (6) inclut deux
