In an imaging device, an image-sensor board is housed in a metallic case, and includes first and second regions. The first region includes first conductor patterns and first insulators constituting a multilayer structure, a first outermost surface on which an image sensor is mounted, and a second outermost surface. The second region includes second conductor patterns and second insulators constituting a multilayer structure. A control circuit board is electrically connected to the first conductor patterns via the second outermost surface. A thermal transfer member is disposed to be in contact with the second region of the image-sensor board for transferring heat generated from the image sensor to the case. The second conductor patterns in the second region include a closest conductor pattern located closest to the thermal transfer member. The closest conductor pattern is electrically isolated from the first conductor patterns.