Abstract: A steam aperture device in a mold for use in preparing a foamed article. The steam aperture device comprises an aperture member extending therethrough and a moving member movably inserted in the aperture member. The aperture member forms a truncated conical wall progressively enlarged toward the end on one side and a cylindrical wall on the other side, both walls having a common axis. The moving member has a truncated conical surface corresponding to the truncated conical wall and a cylindrical surface, the moving member forming a gap between the truncated conical surface and the truncated conical wall when the moving member is raised from the aperture member. A steam passage is formed in at least one of the aperture member and the moving member, one end of the steam passage being opened on the other side and the other end of the steam passage communicating with the gap formed when the moving member is raised.