A manufacturing apparatus for manufacturing a resin molded article includes: an injection molding part configured to inject resin into an injection mold and injection-mold the resin molded article; a control unit configured to control the injection by the injection molding part; a calculation unit configured to calculate a pressure reduction curve for reducing a pressure generated by the injection; and an input unit via which a user inputs a condition of the pressure reduction curve, in which the control unit is configured to control the injection based on the pressure reduction curve.