An image pickup apparatus that can efficiently solve problems caused by heat generated by a heat generating element. The image pickup apparatus including a sensor substrate configured to implement an image sensor, and a main circuit board configured to implement a heat generating element. A length of the main circuit board is longer than a length of the sensor substrate in a width direction of the image pickup apparatus. The main circuit board is aslant arranged to an optical axis of the image pickup apparatus so that a first space part will be provided between the sensor substrate and the main circuit board. A cross section of the first space part in a plane that is parallel to both the optical axis and the width direction is approximately triangle.