According to one embodiment, an imaging device includes a semiconductor substrate having a first conductivity type, a well region which is arranged on a front surface side of the semiconductor substrate and has the first conductivity type, photodiodes which are arranged in the well region and have a second conductivity type, a diffusion layer which is arranged between the photodiodes, supplies a potential to the well region, and has the first conductivity type, an overflow drain layer which is arranged on a back surface side of the semiconductor substrate and has the second conductivity type, an overflow drain electrode which extends from the front surface side of the semiconductor substrate to the overflow drain layer and supplies a bias potential to the overflow drain layer from the front surface side of the semiconductor substrate, and a wiring layer which is arranged on the front surface of the semiconductor substrate.