A molding device for manufacturing a molded product having an arc-shaped bent inner space, the molding device comprising: a pair of molds (10, 20) which is joinable to each other and separable from each other, and is capable of forming a cavity which has a shape corresponding to an outer shape of the molded product in a joined state during molding; a core which has a shape corresponding to an inner shape of the molded product, and is disposed in the inside of the cavity which the pair of molds (10, 20) forms during molding; and a rotation member which is joined to a terminal end of the core, and is rotatable together with the core after molding, wherein the rotation member is rotatable about a predetermined rotation axis (ax) perpendicular to an imaginary plane along an arc as the center of rotation, assuming a side where the cavity is formed during molding as viewed from a member disposed on a side closer to the rotation member than the cavity as one side, and assuming a side opposite to said one side as the other side, the molding device further includes a first fixing member and a second fixing member, wherein the first and second fixing members (50, 60) are capable of fixing the rotation member, the first and second fixing members (50, 60) are configured to fix the core and the rotation member by supporting the rotation member from said other side during molding, and the first and second fixing members (50, 60) allow the rotation member to be rotatable by retracting from said other side of the rotation member after molding, assuming a position where the first and second fixing members (50,60) are arranged when the core is pulled out from the molded product as a retracting position and assuming a position where the first and second fixing members (50,60) are arranged during molding as a fixing position, the first and second fixing members (50, 60) are linearly movable in a direction parallel to the rotation axis (ax) between the retracting position and the fixing position, wherein a moving direction of the first fixing member from the retracting position to the fixing position is opposite to a moving direction of the second fixing member from the retracting position to the fixing position, and as viewed from a position where the retracting position and the fixing position overlap with each other, a positional relationship between the retracting position and the fixing position of the first and second fixing members (50, 60) and the rotation member during molding is not changed even when the first and second fixing members (50, 60) take either the retracting position or the fixing position. a pair of molds (10, 20) which is joinable to each other and separable from each other, and is capable of forming a cavity which has a shape corresponding to an outer shape of the molded product in a joined state during molding; a core which has a shape corresponding to an inner shape of the molded product, and is disposed in the inside of the cavity which the pair of molds (10, 20) forms during molding; and a rotation member which is joined to a terminal end of the core, and is rotatable together with the core after molding, wherein the rotation member is rotatable about a predetermined rotation axis (ax) perpendicular to an imaginary plane along an arc as the center of rotation, assuming a side where the cavity is formed during molding as viewed from a member disposed on a side closer to the rotation member than the cavity as one side, and assuming a side opposite to said one side as the other side, the molding device further includes a first fixing member and a second fixing member, wherein the first and second fixing members (50, 60) are capable of fixing the rotation member, the first and second fixing members (50, 60) are configured to fix the core and the rotation member by supporting the rotation member from said other side during molding, and the first and second fixing members (50, 60) allow the rotation member to be rotatable by retracting from said other side of the rotation member after molding, assuming a position where the first and second fixing members (50,60) are arranged when the core is pulled out from the molded product as a retracting position and assuming a position where the first and second fixing members (50,60) are arranged during molding as a fixing position, the first and second fixing members (50, 60) are linearly movable in a direction parallel to the rotation axis (ax) between the retracting position and the fixing position, wherein a moving direction of the first fixing member from the retracting position to the fixing position is opposite to a moving direction of the second fixing member from the retracting position to the fixing position, and as viewed from a position where the retracting position and the fixing position overlap with each other, a positional relationship between the retracting position and the fixing position of the first and second fixing members (50, 60) and the rotation member during molding is not changed even when the first and second fixing members (50, 60) take either the retracting position or the fixing position.