To provide a device for simply, surely inspecting blocking or no blocking of a crooked passage formed within various kinds of works including a cooling water passage of a cylinder head.

The cylinder head 2 having the cooling water passage 3 having an inlet 7 and an outlet 8 formed on the inside is supported so as to be three- dimensionally swung with an articulated robot 1. An inspection ball 4 having the outer diameter corresponding to the allowable inner diameter of the cooling water passage 3 is put into the inlet 7 of the cooling water passage 3 looking upward. The position of the cooling water passage 3 through which the inspection ball 4 is passed is detected, and at the same time the robot 1 is controlled according to the crooking of the cooling water passage 3 so as to roll and move the inspection ball 4 in the gravity direction to three-dimensionally swing the cylinder head 2.