To make high-quality mousse while reducing the number of components and to prevent the occurrence of situations such as that high-quality mousse can not be made due to a wrong assembly.

A structure 90 for making mousse is arranged in a passage for a mixture of air and a liquid. The structure 90 is constituted of a base body 94 and meshes 95 and 96 fixed to the base body 94. The base body 94 comprises an internal passage open to both sides. The internal passage comprises a cylindrical part 94a open to one side, a cylindrical part 94b open to the other side, and an intermediate part 94c to connect the recessed parts 94a and 94b. The cross section of the intermediate part 94c is smaller than those of the openings of the cylindrical parts 94a and 94b. The openings of the cylindrical parts 94a and 94b are each covered with the meshes 95 and 96. The shapes and sizes of the cylindrical parts 94a and 94b are equal to each other.