A method for mounting a coil onto a stator for a rotary electric machine. The method includes forming a coil piece by winding wire having a flat cross section into a single row lamination state including wire layers that are aligned along a line that is perpendicular to flat surfaces of the wire. The coil piece is formed so that a first portion to be inserted in the slot and a second portion that is not inserted in the slot appear alternately along the coil piece. The method also includes displacing the wire layers at the first portion from one another to change the single row lamination state to a connectively laminated stat e in which the wire layers at the portion to be inserted in the slot each adjacent pair of the wire layers partially overlap with respect to a direction perpendicular to the flat surfaces of the wire. The method further includes inserting the wires of the first portion into the slot, by passing each of the wire layers through the opening of the slot successively from the wire layer at the top of the lamination and displacing each of the wire layers at the first portion from each other.