The present invention provides a method for forming an anode oxide film, in which on the assumption that a direct-current power source is used, a thick anode oxide film can be formed with good productivity within a short time without using special equipment. The method includes allowing a current A0 to pass through an aluminum base material, and includes a step of repeating a first electricity cut-off treatment multiple times, in which when a voltage reaches a voltage V1 during the formation of the film, the passage of electricity is once cut off, this electricity cut-off is continued for a period equal to or longer than an electricity cut-off time T1, and the passage of electricity is then resumed, wherein the voltage V1 and electricity cut-off time T1 satisfy the prescribed expressions.