The present invention provides a method of forming a circuit pattern on an integrally bonded member, the method not requiring a correction step of a laminate film or a resist film which has been necessary at the time of wet treatment of the integrally bonded member. After a circuit pattern forming metal plate 13 is bonded on a part of a ceramic substrate 12 so as to expose an outer peripheral edge portion of the ceramic substrate 12 in an integrally bonded member 10, the integrally bonded member 10 is set on a treating apparatus 30 while being covered with a masking member 20 having a window portion 22 from which the circuit pattern forming metal plate 13 of the integrally bonded member 10 is exposed. Further, the integrally bonded member 10 is pressed with an appropriate pressure from a base plate 11 side so that a boundary surface between a portion 23 surrounding the window portion in the masking member and an exposed surface 16 of the ceramic substrate which is exposed in a metal-ceramic bonded member 14 has a state not allowing a liquid to pass therethrough. Thereafter, a treatment solution 33 for wet treatment is injected from an injection pipe 35 to be in contact with the circuit pattern forming metal plate 13.