To provide a heat radiation structure for an image pickup element which can effectively radiate heat without generating noise.

An image pickup element 11 mounted on an image pickup element mounting substrate 12 is positioned in a rectangular opening of an image pickup element holding plate 13, where an inclination adjustment relative to the image pickup element holding plate 13 is made such that an imaging plane faces an optical axis perpendicularly, and is then fixedly bonded with an adhesive filling the surrounding spacing. The image pickup element mounting substrate 12 has a hole 12d formed in a position corresponding to a rear surface of the image pickup element 11, and a radiation member 18 is brought in contact with the rear surface of the image pickup element 11 via the hole 12d. The radiation member 18 is an elastic member held on a radiation plate 19, and the image pickup element 11 is thermally connected to the radiation plate 19 of high thermal conductivity via the radiation member 18.