An imaging device includes: an image sensor including a light receiving unit, and sensor electrodes； a relay board including at least one rectangular substrate, one or more electronic components, a body part, substrate electrodes, cable electrodes, and pins standing on the substrate and configured to electrically connect the substrate electrodes and the cable electrodes, wherein the substrate electrodes are electrically and mechanically connected with the sensor electrodes； and a cable assembly including cables, and a cable fixing member, wherein cores of the cables exposed on an connection face of the cable fixing member are electrically and mechanically connected with the cable electrodes. A coefficient of thermal expansion of the image sensor, a coefficient of thermal expansion of the relay board, and a coefficient of thermal expansion of the cable assembly vary gradually in descending order or ascending order.
