An apparatus, used for holding a coupling pin (15) at a desired position in a pin-coupled structure regardless of a relative movement of two or more pin-coupled parts in the structure, is disclosed. This pin holding apparatus has two pin holding blocks (3), with an elastic member (5) interposed between the two pin holding blocks, and is inserted into a pin slot (17) with the two holding blocks radially compressed by an external force to reduce the outer diameter of the apparatus. The apparatus elastically expands in the pin slot (17) due to the restoring force of the compressed elastic member (5) when the external force is removed from the apparatus, thus being set in an annular groove formed on the inner surface of the pin slot and holding the pin (15) at its desired position in the pin slot. The pin holding apparatus is easily set in and removed from the pin slot (17). This pin holding apparatus also has an elastic cushion (11), which is positioned at the junction of the pin (15) and the pin holding apparatus, thus almost completely preventing a breakage of the pin.