A method for manufacturing a shaped product constituted by a fiber-reinforced composite material, the method comprising: 1) a prepreg preparation step of obtaining a prepreg, the prepreg preparation step in which a random mat including reinforcing fibers with an average fiber length of 5 mm to 100 mm and a thermoplastic resin is heated up to a temperature of a melting point or more and less than a thermal decomposition temperature in a case where the thermoplastic resin is crystalline, or up to a temperature of a glass transition temperature or more and less than a thermal decomposition temperature in a case where the thermoplastic resin is amorphous such that the random mat is impregnated with the thermoplastic resin; 2) a prepreg arranging step in which the prepreg that is set at the temperature of the melting point or more and less than the thermal decomposition temperature in the case where the thermoplastic resin is crystalline, or at the temperature of the glass transition temperature or more and less than the thermal decomposition temperature in the case where the thermoplastic resin is amorphous is arranged in a mold to be a charge ratio represented by equation (#3) is 50% or more and 100% or less, the mold which is controlled to a temperature less than the melting point temperature in the case where the thermoplastic resin is crystalline or a temperature less than the glass transition temperature in the case where the thermoplastic resin is amorphous; and 3) a molding step in which the prepreg is pressurized within the mold and at the same time, the molding is completed at a temperature less than the melting point in the case where the thermoplastic resin is crystalline, or at a temperature less than the glass transition temperature in the case where the thermoplastic resin is amorphous, to obtain the shaped product, wherein the random mat includes the reinforcing fibers which are substantially two-dimensionally randomly oriented at a fiber areal weight of 25 g/m 2 to 10000 g/m 2, the reinforcing fibers are opened by spraying a gas, reinforcing fiber bundles constituted by the reinforcing fibers of a critical single fiber number or more, the critical single fiber number defined by equation (#1), are included in an amount of 20 Vol% or more and less than 99 Vol% with respect to a total amount of the reinforcing fibers in the random mat, and an average number of the reinforcing fibers in the reinforcing fiber bundles satisfies equation (#2): critical single fiber number = 600 / D 0.7 × 10 4 / D 2 < N < 1 × 10 5 / D 2 wherein, in equation (#1) and equation (#2), D represents an average fiber diameter (μm) of single reinforcing fibers: change ratio % = 100 × base material area mm 2 / mold cavity projection area mm 2 wherein, in equation (#3), a base material area represents a projection area of all the arranged prepreg in a draft direction, and a mold cavity projection area represents a projection area in the draft direction. 1) a prepreg preparation step of obtaining a prepreg, the prepreg preparation step in which a random mat including reinforcing fibers with an average fiber length of 5 mm to 100 mm and a thermoplastic resin is heated up to a temperature of a melting point or more and less than a thermal decomposition temperature in a case where the thermoplastic resin is crystalline, or up to a temperature of a glass transition temperature or more and less than a thermal decomposition temperature in a case where the thermoplastic resin is amorphous such that the random mat is impregnated with the thermoplastic resin; 2) a prepreg arranging step in which the prepreg that is set at the temperature of the melting point or more and less than the thermal decomposition temperature in the case where the thermoplastic resin is crystalline, or at the temperature of the glass transition temperature or more and less than the thermal decomposition temperature in the case where the thermoplastic resin is amorphous is arranged in a mold to be a charge ratio represented by equation (#3) is 50% or more and 100% or less, the mold which is controlled to a temperature less than the melting point temperature in the case where the thermoplastic resin is crystalline or a temperature less than the glass transition temperature in the case where the thermoplastic resin is amorphous; and 3) a molding step in which the prepreg is pressurized within the mold and at the same time, the molding is completed at a temperature less than the melting point in the case where the thermoplastic resin is crystalline, or at a temperature less than the glass transition temperature in the case where the thermoplastic resin is amorphous, to obtain the shaped product, wherein, in equation (#3), a base material area represents a projection area of all the arranged prepreg in a draft direction, and a mold cavity projection area represents a projection area in the draft direction.