To provide a waterproof case for a cellular phone that can store a foldable cellular phone and is excellent in operability.

The waterproof case 1 for a cellular phone stores a foldable cellular phone in which the lower body and the upper body are openably connected, a lower case 2 storing the lower body of the cellular phone, a lower case side holding means 5 provided in the lower case 2 and holding the lower body, an upper case 3 rotatably connected to the lower case 2 through a hinge mechanism portion 4 and storing the upper body of the cellular phone, an engagement portion 6 provided in the upper case 3 and functioning as an upper case side holding means holding the upper body and a sealing member 7 securing liquid tightness. When the lower case 2 and the upper case 3 of the waterproof case 1 are opened and closed by rotating them, the cellular phone stored in the case is opened and closed accordingly.