To provide a coming-out preventing stopper for ribbed pipes which is used to prevent the connected parts of already-connected, ribbed pipes from coming out without cause while connecting ribbed pipes mutually.

This coming-out preventing stopper 1 for use in connecting the ribbed pipes 2, 3 mutually comprises pawl members 1a, 1b to be held into annular grooved portions 2b, 3b formed in the outer periphery of an large- diameter socket 2a of the pipe and the outer periphery of an insertion port 3a inserted into the socket and an annular member 1c for integrating both pawl members with each other.