Abstract: A resonator type silencer used in the air intake duct of an intake system of an internal combustion engine comprises a first case member which includes a generally cup-shaped section. A pipe section is integral with the cup-shaped section and extends through a bottom wall of the cup-shaped section. The pipe section has an inside portion located inside the cup-shaped section. An axially extending slit is formed in the inside portion of the pipe section. First and second flange portions are integral with the pipe section inside portion and located at opposite sides of the slit. The first and second flange portions are integral with the cup-shaped section bottom wall and located parallel with each other. The pipe section inside portion and the flange portions constitute an integral body having a first end face located near an open end of the cup-shaped section.