An imaging device includes: a first case having an opening; a substrate where a first terminal electrically connected with an imaging element is mounted, the substrate being provided in the first case; and a second case closing the opening. The second case includes an accommodation portion accommodating a second terminal designed to be electrically connected with the first terminal. A mating portion capable of being mated with the accommodation portion is secured to the substrate. Inside the mating portion, the first terminal extends along a mating direction of the accommodation portion and the mating portion. The first and second terminals are designed to come into contact with each other while sliding along the mating direction in a mating process of the accommodation portion and the mating portion, and to be elastically deformable in a first direction orthogonal to the mating direction upon contact with each other in the mating process.