PURPOSE: To accomplish thorough cleaning of matters accumulaated on the bottom of water of a simming pool through backward, forward and reciprocating movements of the cleaner in a curve respectively different in direction by means of two sensors mounted thereto.

CONSTITUTION: A carrier 1 carrying thecleaner is sunk down on the bottom of water of a swimming pool and with a pump 6 driven, water is sucked in through a port 4. After the matters accumulsated are captured with a filter 5, the water is jetted out of port 7b. Thus, the cleaner moves forward. A part of the water is fed to a tube 22a, which is expanded eventually bringing the circumference thereof with the horizontal plane of a rotating body 16. Consequently, with the rotatio of a shaft 2a and a transmitting wheel 22, the body 16 turnes clockwise. In this manner, the carrier 1 advances in a slight curve. Upon contact of a sensor 8 with the wall C2, a valve V works to allow the water to jet out of a port 7a. Thus, the c leaner moves backward. Upon contact with the wall C3, a sensor 13 slides to the left reversing the direction in which the rotating body rotates. Thus, the cleaner reciprocoates in an opposite direction depicting the contrary curve from the walls C3 and C1. In this manner, the cleaner moves back and forth and reciprocates in sequence until the bottom of water of the pool is cleaned up thoroughly