There is provided a method of molding a fiber-reinforced plastic hollow part that is capable of molding, with ease and at low costs, a fiber-reinforced plastic hollow part, which has a varying cross-section or a bent portion, in a state in which its weight is sufficiently reduced and in a state where its wall thickness is substantially uniform. A reinforcing fiber (21) and a matrix resin (24) are laminated on the outer circumference of a preformed hollow resin core (10) to obtain a hollow laminate (20). A pressurizing bag (30) is inserted and positioned inside that hollow resin core (10). The hollow laminate (20) is positioned inside a mold (40). Next, heat is applied while pressure is applied to the inside of the pressurizing bag (30) of the hollow laminate (20) positioned inside the mold, thereby integrating the resin and the reinforcing fiber.