PURPOSE: To improve the working environment in the periphery of a nozzle and prevent the public nuisance caused by powdered dust by sealing the periphery of the spraying part of a nozzle with a cover and permitting the powdered dust in the cover to be sucked into a cleaner, in a sand blast apparatus for a hull in a dock.

CONSTITUTION: A nozzle boss 2 equipped with a nozzle 3 on the front surface is supported in swingable ways onto a frame body 1 through a spherical bearing, and a sand-blast spray driving apparatus is connected onto said nozzle 3 through a flexible hose 4. The top edges of the piston rods 5a and 6a of cylinder units 5 and 6 are connected onto the back surface of the nozzle boss 2 through a ball joint. Said cylinder units 5 and 6 swing the nozzle boss 2 vertically and right and left. The base edge part of a cover 7 which surrounds the nozzle 3 and whose front side is opened is fixed at the front edge of the frame body 1. A duct 10 which is connected to a suction cleaner is opened onto the cover 7. Sand- blasting work for the side of a hull in a dock is carried out by installing said frame body 1 onto forklifts, etc.