An insulated circuit substrate manufacturing method of the present invention includes a metal piece disposing step of disposing the metal piece in a circuit pattern shape on a resin material serving as the insulating resin layer and a bonding step of bonding the insulating resin layer and the metal piece by pressurizing and heating the resin material and the metal piece at least in a laminating direction. In the bonding step, the metal piece and the resin material are pressurized in the laminating direction by a pressurizing jig that includes a cushion material disposed on a side of the metal piece and a guide wall portion disposed at a position facing a peripheral portion of the cushion material, and the peripheral portion of the cushion material is brought into contact with the guide wall portion during pressurization.