PURPOSE: To obtain the title culture stopper having high gas permeability and free from lowering of the permeability and useful for long-term culture of a germ by arranging a zeolite having molecular sieve characteristics in a state dispersed in a rubber material.

CONSTITUTION: The objective culture stopper obtained by arranging a zeolite having molecular sieve characteristics in a state dispersed in a rubber material. Furthermore, the zeolite is a zeolite subjected to hydrophobic treatment with an organosilazane [e.g. 1,3-bisperfluoroalkyl)ethyl-1,1,3,3-tetramethyl-1,3- disilazane] and further antimicrobial effects are preferably provided to the rubber by a metal ion dope.