An ink cassette comprising: a supply bobbin on which an ink ribbon is wound; a winding bobbin for winding up the ink ribbon fed from the supply bobbin; and an enclosure (304, 305, 306) including a supply bobbin storage portion that rotatably stores the supply bobbin and a winding bobbin storage portion that rotatably stores the winding bobbin, wherein in each of the supply bobbin storage portion and the winding bobbin storage portion, an opening (316a, 316b) is provided in one side surface of the enclosure (304, 305, 306), and an elastic piece (314a, 314b) and a rotation restricting portion (319a, 319b) are provided, wherein the one side surface of the enclosure (304, 305, 306) forms a side surface that is substantially orthogonal to the rotational axes of the supply bobbin and the winding bobbin, the supply bobbin and the winding bobbin are capable of moving in a rotational axis direction, and each has a rotation-restricted portion (301c, 302c), and the rotation-restricted portions (301c, 302c) engage with the rotation restricting portions (319a, 319b) and restrict rotation of the supply bobbin and the winding bobbin, characterized in that the supply bobbin and the winding bobbin are each biased by the elastic pieces (314a, 314b) in the rotational axis direction of the supply bobbin and the winding bobbin toward the rotation restricting portions (319a, 319b), the elastic piece (314a, 314b) is provided within each of the openings (316a, 316b), and the rotation restricting portions (319a, 319b) are provided on an inner side of another side surface of the enclosure (304, 305, 306), and each of the elastic pieces (314a, 314b) has a bent portion (315a, 315b) that bends in a direction substantially orthogonal to a biasing direction of the elastic piece (314a, 314b). a supply bobbin on which an ink ribbon is wound; a winding bobbin for winding up the ink ribbon fed from the supply bobbin; and an enclosure (304, 305, 306) including a supply bobbin storage portion that rotatably stores the supply bobbin and a winding bobbin storage portion that rotatably stores the winding bobbin, wherein in each of the supply bobbin storage portion and the winding bobbin storage portion, an opening (316a, 316b) is provided in one side surface of the enclosure (304, 305, 306), and an elastic piece (314a, 314b) and a rotation restricting portion (319a, 319b) are provided, wherein the one side surface of the enclosure (304, 305, 306) forms a side surface that is substantially orthogonal to the rotational axes of the supply bobbin and the winding bobbin, the supply bobbin and the winding bobbin are capable of moving in a rotational axis direction, and each has a rotation-restricted portion (301c, 302c), and the rotation-restricted portions (301c, 302c) engage with the rotation restricting portions (319a, 319b) and restrict rotation of the supply bobbin and the winding bobbin, characterized in that the supply bobbin and the winding bobbin are each biased by the elastic pieces (314a, 314b) in the rotational axis direction of the supply bobbin and the winding bobbin toward the rotation restricting portions (319a, 319b), the elastic piece (314a, 314b) is provided within each of the openings (316a, 316b), and the rotation restricting portions (319a, 319b) are provided on an inner side of another side surface of the enclosure (304, 305, 306), and each of the elastic pieces (314a, 314b) has a bent portion (315a, 315b) that bends in a direction substantially orthogonal to a biasing direction of the elastic piece (314a, 314b).