An imaging device, which is disposed in a tip portion of the endoscope, includes: a lens barrel that holds an objective optical system receiving image light of a portion to be observed and forming an image a rectangular prism changing the direction of a light path of image light, which has passed through the objective optical system, at a right angle an imaging element of which an imaging surface is disposed along a plane orthogonal to the direction of the light path changed by the rectangular prism and a board on which the imaging element is mounted. The board includes a tip-side region that extends toward a tip side from an imaging element mounting region in which the imaging element is mounted, and an electronic component of a drive circuit necessary to drive the imaging element is mounted in the tip-side region.
