A substrate manufacturing method includes an inner layer circuit forming step for partially removing metal films from an insulating base material (2), on both surfaces of which the metal films are stuck, and forming an inner layer circuit (3); and an insulating layer forming step for applying first insulating resin (4) to each of both the surfaces of the insulating base material (2) with an inkjet system and forming an insulating layer (5). In the insulating layer forming step, a via hole (6) from which the inner layer circuit (3) is partially exposed is formed simultaneously with the application of the first insulating resin (4). Consequently, a step of separately forming a via hole with a laser or the like is unnecessary, expenses are relatively low, and it is possible to simplify a manufacturing process.