To change exposure in accordance with water depth on taking underwater photography without operating to change from land photography.

A waterproof film unit with a lens is composed of a waterproof case and a unit main body. The waterproof case is composed of a main case 5 and a cap. A deformable member 13 is attached to the upper face of the main case 5. A diaphragm varying mechanism 40 is disposed inside a light shielding cylinder. A left diaphragm blade 42 and a right diaphragm blade 43 of the diaphragm varying mechanism 40 are rotatably attached to a base 41. The left diaphragm blade 42 and the right diaphragm blade 43 rotate in a direction to open the diaphragm when a rotation lever 45 rotates clockwise, and the blades rotate in a direction to close the diaphragm when the rotation lever 45 rotates counterclockwise. The rotation lever 45 is biased counterclockwise by a coil spring 47. When a pressure transfer lever 48 is moved downward according to downward deformation of the deformable member, the rotation lever rotates clockwise.