An imaging device according to the present disclosure includes a plurality of pixels each including a first light-receiving element and a second light-receiving element, the plurality of pixels including a first pixel. The imaging device further includes a generating section that generates a first detection value on a basis of a light-receiving result by the first light-receiving element of each of the plurality of pixels, and generates a second detection value on a basis of a light-receiving result by the second light-receiving element of each of the plurality of pixels. The imaging device further includes a diagnosis section that performs a diagnosis processing on a basis of a detection ratio that is a ratio between the first detection value and the second detection value in the first pixel.