To provide an electronic imaging device having mirror-scanning function, capable of making the substantial number of pixels equal to or exceed that of HDTV specification and that of silver-salt, while using conventional small-sized, low-cost NTSC, PAL and HDTV specification imaging devices.

An imaging optical system 21 is constituted of; a 1st lens group 11, including a negative lens 11a positioned closest to the object side and also including a positive lens 11b, a rotating mirror 12, an aperture diaphragm 13, and a 2nd positive lens group 14 a part of or the whole of which can be shifted on an optical axis. The imaging optical system 21 and the electronic imaging device 18 for receiving light passing through the imaging optical system 21 are arranged in order from the object side, and conditional expressions 7mm<d<25mm, 0.1<n1-n2<0.4 and 2<(r1+r2)/(r1-r2)<10 are satisfied simultaneously. Here, d denotes the distance between the rotational center position of the mirror 12 and the pupil position of the imaging optical system 21, n1 denotes the refractive index of the positive lens 11b, n2 denotes the refractive index of the negative lens 11a, r1 and r2 separately denotes the curvature radius of the positive lens 11b on the object side and on the image side.