A method includes: shaping a transparent belt base having opposite ends into a tubular shape with the ends thereof spaced away from or in contact with each other to make a tubular belt base; superposing a release base having a liquid layer of a curable polyurethane elastomer on and in contact with the outer periphery of the tubular belt base inclusive of the space or contact portion between the ends in a manner that the liquid layer is sandwiched in between the transparent belt base and the release base; curing the curable polyurethane elastomer while the liquid layer being sandwiched between the transparent belt base and the release base to form a transparent polyurethane elastomer layer; stripping the release base off the transparent polyurethane elastomer layer; and connecting the ends of the tubular transparent belt base spaced away from or in contact with each other to form a joint.