Method of manufacturing and manufacturing apparatus for an assembled product

An attachment unit for attaching a seal body in a manufacturing apparatus that manufactures an assembled product, which includes a component main body and a ring-shaped seal body that has been attached to a ring-shaped inner circumferential surface of the component main body, the attachment unit comprising:

• a pair of guide members that support the ring-shaped seal body to be attached to a ring-shaped channel formed in the inner circumferential surface of the component main body;
• a rod-shaped deformation engagement member that moves a portion of the seal body inward in a radial direction to cause deformation of the seal body, and holds the seal body by acting in concert with the pair of guide members, the rod-shaped deformation engagement member having a shaft, configured to extend in a direction parallel to a center axis of the seal body, the shaft having a curved surface and the curved surface of the shaft configured to engage an engaged portion of the seal body and move the engaged portion inward in the radial direction;
• and
• a ring attaching mechanism that moves the seal body supported by the ring pair of guide members to the attachment channel by acting in concert with the rod-shaped deformation engagement member and attaches the seal body by acting in concert with the rod-shaped deformation engagement member.