A tape cassette comprising: a generally rectangular box-like housing having a top wall , a bottom wall , and a side wall defining a periphery of the housing , the top wall and the bottom wall form rectangular planar portions; a first cavity provided in the bottom wall and disposed in a first corner portion of the bottom wall and extending from the bottom wall and disposed between a tape containing area and the periphery; a second cavity provided in the bottom wall , disposed in a second corner portion and extending from the bottom wall , the second corner portion being disposed between a tape containing area and the periphery and located at a diagonal position with respect to the first corner portion of the bottom wall; at least one tape wound and mounted within the housing in a tape containing area defined within the periphery, the at least one tape including a first tape disposed in a first area , the first tape having a hole at a center of winding, and the first area being one of two areas (30C and 30D) formed by dividing the housing with respect to a straight line (K) connecting the first cavity and the second cavity ; and a third cavity that extends in the hole of the first tape from the bottom wall , wherein the second cavity is a guide hole for guiding the tape cassette when the tape cassette is installed in or removed from a tape printer characterized in that the second cavity includes an internal cylindrical wall forming a shaft hole connecting the opening provided in the bottom wall and another opening provided in the top wall , wherein the openings are provided at positions opposing each other. a generally rectangular box-like housing having a top wall , a bottom wall , and a side wall defining a periphery of the housing , the top wall and the bottom wall form rectangular planar portions; a first cavity provided in the bottom wall and disposed in a first corner portion of the bottom wall and extending from the bottom wall and disposed between a tape containing area and the periphery; a second cavity provided in the bottom wall , disposed in a second corner portion and extending from the bottom wall , the second corner portion being disposed between a tape containing area and the periphery and located at a diagonal position with respect to the first corner portion of the bottom wall; at least one tape wound and mounted within the housing in a tape containing area defined within the periphery, the at least one tape including a first tape disposed in a first area , the first tape having a hole at a center of winding, and the first area being one of two areas (30C and 30D) formed by dividing the housing with respect to a straight line (K) connecting the first cavity and the second cavity ; and a third cavity that extends in the hole of the first tape from the bottom wall , wherein the second cavity is a guide hole for guiding the tape cassette when the tape cassette is installed in or removed from a tape printer characterized in that the second cavity includes an internal cylindrical wall forming a shaft hole connecting the opening provided in the bottom wall and another opening provided in the top wall , wherein the openings are provided at positions opposing each other. <EOS>