A seat rail structure for a motorcycle, the seat rail structure comprising a seat rail configured to be installed on a vehicle body of a motorcycle, wherein: the seat rail includes two lateral members spaced apart from each other in a width direction of the vehicle body and a first coupling member configured to couple the two lateral members to each other and to allow a seat to be placed thereon; each of the two lateral members and the first coupling member is configured to have a laminated structure in which a plurality of layers made of a fiber reinforced resin are laminated; each of the lateral members includes a vertical wall configured to be located at a lateral side in the width direction of the vehicle body and an upper flange configured to protrude toward a center in the width direction of the vehicle body from an upper edge of the vertical wall; and the first coupling member includes two upper surface contact portions that are in contact with the upper flanges of the two lateral members, respectively, each of the upper surface contact portions includes an outer edge configured to face outward in the width direction of the vehicle body; an upper fastening portion is provided to fasten each of the upper surface contact portions and the upper flange which is in contact with the each of the upper surface contact portions, together; characterized in that the first coupling member includes two side surface contact portions extending downward from the outer edges of the two upper surface contact portions, respectively; the two side surface contact portions are in contact with the vertical walls of the two lateral members, respectively; and a first side surface fastening portion is provided to fasten together each of the side surface contact portions and the vertical wall, which is in contact with the each of the side surface contact portions. the seat rail includes two lateral members spaced apart from each other in a width direction of the vehicle body and a first coupling member configured to couple the two lateral members to each other and to allow a seat to be placed thereon; each of the two lateral members and the first coupling member is configured to have a laminated structure in which a plurality of layers made of a fiber reinforced resin are laminated; each of the lateral members includes a vertical wall configured to be located at a lateral side in the width direction of the vehicle body and an upper flange configured to protrude toward a center in the width direction of the vehicle body from an upper edge of the vertical wall; and the first coupling member includes two upper surface contact portions that are in contact with the upper flanges of the two lateral members, respectively, each of the upper surface contact portions includes an outer edge configured to face outward in the width direction of the vehicle body; an upper fastening portion is provided to fasten each of the upper surface contact portions and the upper flange which is in contact with the each of the upper surface contact portions, together; characterized in that the first coupling member includes two side surface contact portions extending downward from the outer edges of the two upper surface contact portions, respectively; the two side surface contact portions are in contact with the vertical walls of the two lateral members, respectively; and a first side surface fastening portion is provided to fasten together each of the side surface contact portions and the vertical wall, which is in contact with the each of the side surface contact portions.