A joining method for members includes: providing a steel component 10 including insertion holes 14a and 15a, an aluminum pipe 20 having a hollow shape, and a support component 30; inserting the aluminum pipe 20 into the insertion holes 14a and 15a of the steel component 10; and enlarging the aluminum pipe 20 through deformation and joining the aluminum pipe 20 to the steel component 10 by press-fitting. The press-fit joining is performed while at least part of the support component 30 is disposed in a press-fitting region.