PROBLEM TO BE SOLVED: To provide a method for producing a fiber-reinforced thermoplastic resin-integrated structure, in which method satisfactorily high bonding strength of bonded joints can be realized easily and surely.SOLUTION: The method for producing the fiber-reinforced thermoplastic resin-integrated structure comprises the steps of: forming grid-shaped grooves or grid-shaped convex stripes on the joint surface of at least one of a fiber-reinforced thermoplastic resin molding (I) which strengthened fiber is oriented randomly and an adherend (II); and welding the molding (I) to the adherend (II) by ultrasonic welding while exerting 2-6 MPa surface pressure on the grid-shaped grooves or 0.2-3 MPa surface pressure on the grid-shaped convex stripes.
