A method for mounting coil onto stator for rotary electric machine. The method includes forming coil pieces by winding wire with flat cross section into single row lamination state including wire layers aligned along perpendicular line to flat surfaces of wire. The coil is formed for first portion to be inserted in slot and second portion not inserted in slot appear alternately along the coil. The method displaces wire layers at the first portion changing the single row lamination state to connectively laminated state where wire layers at portion to be inserted in slot each adjacent pair of the wire layers partially overlap with respect to direction perpendicular to flat wire surfaces. The method includes inserting wires of first portion into slot, passing each wire layer through slot opening successively from the top wire layer of lamination and displacing each wire layer at first portion from each other.