To make the size of a personal digital assistant smaller and provide the personal digital assistant at a lower price by enabling optical zooming and electronic zooming, without increasing the number of operation buttons, etc., in an imaging device provided for the personal digital assistant or the like.

The imaging device includes an imaging element which converts a subject image into an electrical signal; a zooming mechanism which varies photographing magnification, in such a manner that a variable power optical system in a photographing optical system which forms the subject image onto the imaging element is moved in the direction of the optical axis by the rotating operation of a rotation operating member, having the optical axis of the imaging optical system as its axis; and a detection means for detecting the rotation position of the rotation operating member. In the imaging device, positional information from the detection means during imaging is used as a signal for the magnification detection control of the variable power optical system or the magnification control of electronic zooming.