PURPOSE: To provide a cleaning machine capable of efficiently cleaning while traveling on a vertical surface, a ceiling surface, etc., by supporting an injection unit to return a blasting material to an injecting means on a tread unit having a magnetic tread to be rotated after the injected blasting material and pieces are retrieved.

CONSTITUTION: This blast machine comprises a pair of right and left tread units 2 and an injection unit 1 supported on a frame member 4 turnably connected between both tread units 2. Each tread unit 2 is provided with a magnetic tread in which a plurality of magnets 48 are carried by a chain 35 wound between two sprockets pivotably supported by a frame 6, and turned by a drive motor 20. The injection unit 1 is provided with a pair of injection wheels to inject the blasting material to an area to be injected, and a returning passage 70 to receive the blasting material of the blast machine together with broken pieces. The retrieved blasting material and broken pieces are introduced in a separator 78 by a screw conveyor 74, and the blasting material from which the broken pieces are separated is fed again to the blast wheels.