A power generation device comprising: a rotation member configured to rotate by an externally applied operation force, wherein the rotation member is a plate-like member made of soft magnetic material; a bobbin made of two spools (9a,9b) fitted together, wherein each spool covers the long side of the rotation member; a coil mounted on the bobbin; first and second plate-like support members (2a, 2b) made of soft magnetic material; and a permanent magnet, wherein: the rotation member is supported inside the bobbin such that both end portions of the rotation member extend from the bobbin; the support members (2a, 2b) are fitted to the bobbin such that the ends (3a, 3b, 3c, 3d) of the support members (2a, 2b) sandwich the ends of the rotation member; the permanent magnet is sandwiched by the support members (2a, 2b), such that the ends (3a, 3b, 3c, 3d) of the support members (2a, 2b) attract the ends of the rotation member in such way that the rotation member is constantly supported in an orientation of diagonally passing through the interior of the bobbin by the magnetic force of the ends (3a, 3b, 3c, 3d) positioned diagonally with respect to each other with the rotation member therebetween, and wherein the power generation device is configured to induce a current to the coil by causing a magnetic flux of the permanent magnet passing through the coil to fluctuate in cooperation with the rotation of the rotation member, characterized in that a protrusion is arranged inside the bobbin in an extending manner on the spool in the width direction of the rotation member; and the rotation member and the protrusion do not touch each other such that a clearance is formed between the rotation member and the protrusion when the rotation member is supported in a diagonal orientation. a rotation member configured to rotate by an externally applied operation force, wherein the rotation member is a plate-like member made of soft magnetic material; a bobbin made of two spools (9a,9b) fitted together, wherein each spool covers the long side of the rotation member; a coil mounted on the bobbin; first and second plate-like support members (2a, 2b) made of soft magnetic material; and a permanent magnet, wherein: the rotation member is supported inside the bobbin such that both end portions of the rotation member extend from the bobbin; the support members (2a, 2b) are fitted to the bobbin such that the ends (3a, 3b, 3c, 3d) of the support members (2a, 2b) sandwich the ends of the rotation member; the permanent magnet is sandwiched by the support members (2a, 2b), such that the ends (3a, 3b, 3c, 3d) of the support members (2a, 2b) attract the ends of the rotation member in such way that the rotation member is constantly supported in an orientation of diagonally passing through the interior of the bobbin by the magnetic force of the ends (3a, 3b, 3c, 3d) positioned diagonally with respect to each other with the rotation member therebetween, the rotation member is supported inside the bobbin such that both end portions of the rotation member extend from the bobbin; the support members (2a, 2b) are fitted to the bobbin such that the ends (3a, 3b, 3c, 3d) of the support members (2a, 2b) sandwich the ends of the rotation member; the permanent magnet is sandwiched by the support members (2a, 2b), such that the ends (3a, 3b, 3c, 3d) of the support members (2a, 2b) attract the ends of the rotation member in such way that the rotation member is constantly supported in an orientation of diagonally passing through the interior of the bobbin by the magnetic force of the ends (3a, 3b, 3c, 3d) positioned diagonally with respect to each other with the rotation member therebetween, and wherein the power generation device is configured to induce a current to the coil by causing a magnetic flux of the permanent magnet passing through the coil to fluctuate in cooperation with the rotation of the rotation member, characterized in that a protrusion is arranged inside the bobbin in an extending manner on the spool in the width direction of the rotation member; and the rotation member and the protrusion do not touch each other such that a clearance is formed between the rotation member and the protrusion when the rotation member is supported in a diagonal orientation.