To store the PET bottles in a stacked condition by protecting the pet bottle by a cylindrical container, moving a rotary cutting blade having a handle on its upper part up and down to be rotated and stopped in the container for cutting the standing PET bottle from four side directions, and washing the inside of the bottle.

A cylindrical container 1 is put on a PET bottle 3 to be cut, an upper handle is used as an operation part, and the handle is pushed downward, so that the electric current flows to a motor, and a side surface of the PET bottle 3 is cut from its four directions by four rotary cutting blades 2 mounted inside of the cylindrical container 1. By placing a force spring 5 in the handle part 4, the rotary cutting blades 2 pushed downward are upwardly returned only by releasing the pushing-down force of the handle, whereby the motor is stopped and the rotation of the rotary cutting blades 2 is stopped. The PET bottles can be cut regardless of dimensions.