PURPOSE: To enable the easy detection of a spot of leak by introducing a colored fluid into a component to be inspected and by making it flow out of a crack or the like if any.

CONSTITUTION: An inspecting medium supply unit 2 is provided with a colored fluid accommodating element 4 wherein smoke obtained by burning oil is accommodated under a prescribed pressure, and the inspecting medium supply unit 2 and an inspecting medium discharging unit 3 are connected to a component 1 to be inspected. When the compressor of the inspecting medium supply unit 2 operates and a solenoid valve 6 opens, the accommodating element 4 sends the smoke under a pressure to the component 1 through a pipe 2a. A solenoid valve 7 remains closed on the occasion, and if there is any crack, the smoke permeating the inside of the component 1 flows outside with an increase in the internal pressure, wherefrom a spot of leak is discerned. When the solenoid valve 7 is opened after a prescribed time passes, the smoke flows through a pipe 3a, and the leak can be detected again by detecting the flow pressure of the smoke by means of a leak tester 8.