Provided is a thermal melting three-dimensional printer with which it is possible to suppress molding defects.　The present invention provides a thermal melting three-dimensional printer that comprises an extruder and a push-in mechanism. The extruder comprises a hopper, a cylinder, and a nozzle. The hopper is configured to be capable of feeding pellets into the cylinder through a raw material feed port formed in the cylinder. The extruder is configured to form molten resin by melting and kneading, within the cylinder, the pellets fed into the cylinder, and then form a strand by extruding the molten resin through the nozzle. The push-in mechanism is configured to push the pellets placed on a placement surface of the hopper into the cylinder through the raw material feed port.