A tape cassette capable of ensuring firm joining between different resin layers of a casing and exhibiting a good aesthetic property. The tape cassette includes a casing consisting of upper casing member and lower casing member which are integrally made into a two-layer structure of a primary resin layer and a secondary resin layer integrally formed by two-layer molding. The secondary resin layer is formed with a plurality of penetrations and the primary resin layer is joined to the secondary resin layer in a manner to be fitted in the penetrations, resulting in being integral with the secondary resin layer.
