Vehicle seat and coupling method for use in vehicle seat

A coupling method for use in a vehicle seat including a seat cushion having a side frame, a floor-side seat supporting member, and a coupling bracket that couples the side frame to the floor-side seat supporting member, the coupling bracket being fixed to the side frame by welding joining, the coupling method comprising:

• overlapping an upper part of the coupling bracket with a lower part of the side frame in an overlapped region;
• welding, in a first welding joining portion, an edge of a first member as one of the coupling bracket and the side frame to a second member as the other of the coupling bracket and the side frame, from a first member side;
• providing a joining hole that extends through the first member in a plate thickness direction of the first member at a position in the overlapped region other than the first welding joining portion;
• and
• welding, in a second welding joining portion, an edge of the joining hole to the second member, from the first member side.