A resin garnish installation structure installed to a vehicle body exterior surface, having a resin garnish which extends along a longitudinal direction thereof, the resin garnish including: an exterior surface which is level with the vehicle body exterior surface; a first edge which extends along the longitudinal direction; a second edge which is provided on an opposite side of the first edge and extends along the longitudinal direction; and an end part provided at a tip in the longitudinal direction, wherein in a vicinity of the end part, the second edge gradually curbs toward the first edge, and the second edge joins the first edge at the end part, and the resin garnish is installed so that a gap is formed between the end part and the vehicle body exterior surface, the gap becoming wider as it gets closer to the tip of the resin garnish.