A method for manufacturing a three-dimensional shaped object according to the present disclosure includes: a plasticizing step of plasticizing at least a part of a shaping material including a first fiber material and a thermoplastic resin to generate a plasticized material to be discharged from a nozzle opening for shaping a three-dimensional shaped object; a fiber introducing step including either a step of introducing a second fiber material longer than the first fiber material into the shaping material or the plasticized material before being discharged from the nozzle opening, or a step of introducing the second fiber material into the plasticized material after being discharged from the nozzle opening; and a shaping step of shaping the three-dimensional shaped object including the first fiber material and the second fiber material.