A power transmission device comprising: a first rotation body and a second rotation body that are arranged on the same rotation axis; a connecting member that connects the first rotation body and the second rotation body; a first connecting structure that connects one end portion of the connecting member to the first rotation body and regulates detachment of the connecting member from the first rotation body; and a second connecting structure that connects the other end portion of the connecting member to the second rotation body and permits detachment of the connecting member from the second rotation body, wherein the second connecting structure includes: a columnar body provided on the second rotation body, the columnar body extending along the rotation axis through the other end portion; a projecting body formed along the other end portion from an end portion of the columnar body that is closer to the other end portion; and an elastic body configured to press the other end portion in a direction of the axis, and generate a frictional force for transmitting power between a rotation member including the columnar body and the second rotation body, and the other end portion, characterized in that the second connecting structure further includes a slit in which the columnar body is inserted formed from an edge of the other end portion along a rotation locus of the columnar body; the other end portion of the connecting member is formed to be larger than a remaining portion of the connecting member when viewed from the direction of the axis, and a recessed portion that is recessed toward an outer peripheral side of the second rotation body is formed at a portion of the other end portion that is directed to a shaft center side of the second rotation body. a first rotation body and a second rotation body that are arranged on the same rotation axis; a connecting member that connects the first rotation body and the second rotation body; a first connecting structure that connects one end portion of the connecting member to the first rotation body and regulates detachment of the connecting member from the first rotation body; and a second connecting structure that connects the other end portion of the connecting member to the second rotation body and permits detachment of the connecting member from the second rotation body, wherein the second connecting structure includes: a columnar body provided on the second rotation body, the columnar body extending along the rotation axis through the other end portion; a projecting body formed along the other end portion from an end portion of the columnar body that is closer to the other end portion; and an elastic body configured to press the other end portion in a direction of the axis, and generate a frictional force for transmitting power between a rotation member including the columnar body and the second rotation body, and the other end portion, characterized in that the second connecting structure further includes a slit in which the columnar body is inserted formed from an edge of the other end portion along a rotation locus of the columnar body; the other end portion of the connecting member is formed to be larger than a remaining portion of the connecting member when viewed from the direction of the axis, and a recessed portion that is recessed toward an outer peripheral side of the second rotation body is formed at a portion of the other end portion that is directed to a shaft center side of the second rotation body. a columnar body provided on the second rotation body, the columnar body extending along the rotation axis through the other end portion; a projecting body formed along the other end portion from an end portion of the columnar body that is closer to the other end portion; and an elastic body configured to press the other end portion in a direction of the axis, and generate a frictional force for transmitting power between a rotation member including the columnar body and the second rotation body, and the other end portion, characterized in that the second connecting structure further includes a slit in which the columnar body is inserted formed from an edge of the other end portion along a rotation locus of the columnar body; the other end portion of the connecting member is formed to be larger than a remaining portion of the connecting member when viewed from the direction of the axis, and a recessed portion that is recessed toward an outer peripheral side of the second rotation body is formed at a portion of the other end portion that is directed to a shaft center side of the second rotation body.