PROBLEM TO BE SOLVED: To provide a method for preventing odor leakage of piping that can prevent the occurrence of odor with various piping works, and an aerosol for use in the same.SOLUTION: An aerosol is obtained by filling a foam-forming aerosol composition containing a surface active agent of 70-80% in mass% and a propellant as a remainder. The aerosol is used for injecting the aerosol composition toward the inside of piping 3 to thereby form a foam block body 4 without air permeability that can stay in the middle of the passage of the piping 3. By this foam block body 4, the odor in the piping 3 is prevented from leaking to the outside. Further, the foam block body 4 can be washed out with water.
