An image rotation adapter that is configured to be detachably mounted between an image capturing lens and a camera main body in a camera and includes a first prism configured to invert the object image passed through the image capturing lens by reflecting an odd number of times object light passed through the image capturing lens and a second prism that is supported rotatably about the optical axis, and that is configured to further invert the object image inverted by the first prism by reflecting an odd number of times the object light passed through the first prism; an operation device configured to perform an operation to rotate the second prism; and a relay optical system configured to re-form the object image passed through the second prism on the light receiving surface of the image pickup device.