A support apparatus for a guide pin contains: an accommodation tube, an upright post, a connection shaft, a holder, two side plates, a guiding trench, a roller, a guide pin, and a driving mechanism. The accommodation tube includes a fork, a through groove, and an elongated slot. The upright post includes two first coupling segments, and the connection shaft passes through the fork and is located on the accommodation tube. The holder includes two parallel joining extensions, and the two side plates are separated from each other. The guiding trench passes through the holder, and the roller is accommodated between the two side plates and is rotatably fitted with the connection shaft, and a part of the guide pin inserts into the guiding trench. The driving mechanism is accommodated in the elongated slot and is in connection with the two first coupling segments and the two joining extensions.