A foam generator for compression receptacles is configured such that liquid contents pumped by an internal pressure as a result of directly compressing a compression receptacle, having the liquid contents stored therein, are mixed with air in a gas-liquid mixing chamber and, at the same time, directly discharged in the form of foam. Accordingly, the foam generator not only is capable of preventing the corruption of the liquid contents, which are not in contact with any separate metal member, but also further improves product responsiveness, since the contents are instantly discharged in the form of foam by compressing the compression receptacle.