To provide a suction cup mechanism for a wall surface moving machine capable of preventing damage of a vacuum pump etc. and improving maintenance performance and work efficiency.

The suction cup mechanism 1 for attaching a suction cup 10 to an object by reducing air pressure inside the suction cup 10 includes an air suction mechanism communicated with inside of the suction cup 10 and sucking air inside the suction cup 10. The air suction mechanism includes: a suction means 32 connected to the suction cup 10 by an air flow passage 35; and a suction force generation mechanism interposed in the air flow passage 35. The suction force generation mechanism includes a separation member 45 separating the suction means 32 and outside from each other. The separation member 45 is arranged so that a volume between the separation member 45 and an opening of the suction cup 10 increases when air is sucked by the suction means 32.