In an automatic coupler for a model railroad car, a coupler body includes a knuckle coupler member formed of a coupler trunk having a knuckle portion and an engagement portion, and a receiving coupler member formed of a coupler trunk having a receiving portion and an engagement portion. A holder includes a lower holder member having a holder plate, a holder shaft projecting from the holder plate and adapted to engage with the engagement portions, and a spring portion adapted to surround the engagement portions. The holder plate, holder shaft, and the spring portion are integrally formed, and an upper holder member is adapted to be fixed to the lower holder member with the coupler body interposed between. The coupler body and the holder have a guide mechanism that allows the coupler body to follow a curve when the car travels on the curve.