Vehicle arm member and its manufacturing method

Object of the present invention is to provide a cross section without an abrupt change, easy to manufacture and helps reduce the cost of a vehicle arm member. The arm member is a vehicle, by a first plane in a second direction and the direction perpendicular to the first direction intersecting the extending constituted i.e. flat workpiece (W) by pressing a stepwise manner, whereby the two sides of the second molded abutting engagement direction, characterized by comprising: a cylindrical portion (10), provided along a first direction, and having a cylindrical shape; bracket portion (20), disposed in a circle direction ends of the first cylindrical portion, and the outer diameter of the expanded outwardly in a first direction; two flange portions (30), disposed facing the bracket portion in a second direction, the second direction and face each at a position a through hole (20H).