A high frequency sewing machine comprising: a work material mounting plate which is attached to an upper wall of a sewing machine bed section and slidingly movably mounts a work material with a thermoplastic resin tape interposed between overlapped portions of a fiber cloth; an intermittent transfer device which is disposed in the bed section below the work material mounting plate and alternately repeats a mode for abutting against a lower surface of the work material mounted on the work material mounting plate and transferring the work material along a horizontal surface in a specific processing advance direction, and a mode for separating from the lower surface of the work material and stopping the transfer of the work material; a presser foot which is disposed above the work material mounting plate cooperates with the intermittent transfer device to transfer the work material in the processing advance direction, and is reciprocatingly movable up and down to resiliently press the work material during time when a transfer is stopped; and characterized in that it comprises an upper planar electrode which is disposed above the work material mounting plate so as to be reciprocatingly movable up and down and has an electrode surface with a width not less than a transfer width of feed dogs of the intermittent transfer device in the processing advance direction, and a lower planar electrode which is disposed and secured in the bed section below the work material mounting plate and has an electrode surface flush with an upper surface of the work material mounting plate and is opposed to the electrode surface of the upper electrode, wherein in a state where the work material is held between the electrode surface of the upper planar electrode and the electrode surface of the lower planar electrode by moving down the upper planar electrode during the time when the transfer by the intermittent transfer device is stopped, the overlapped portions of the fiber cloth are continuously bonded together by allowing the thermoplastic resin tape to melt under high frequency dielectric heating by applying high frequency power between a pair of the upper and lower planar electrodes, wherein the intermittent transfer device comprises the feed dogs disposed in slot-like elongated holes formed in the work material mounting plate, and a feed dogs drive mechanism which causes synthetic circular movement of the feed dogs in vertical and horizontal directions in the slot-like elongated holes, wherein the presser foot serves as the upper planar electrode. a work material mounting plate which is attached to an upper wall of a sewing machine bed section and slidingly movably mounts a work material with a thermoplastic resin tape interposed between overlapped portions of a fiber cloth; an intermittent transfer device which is disposed in the bed section below the work material mounting plate and alternately repeats a mode for abutting against a lower surface of the work material mounted on the work material mounting plate and transferring the work material along a horizontal surface in a specific processing advance direction, and a mode for separating from the lower surface of the work material and stopping the transfer of the work material; a presser foot which is disposed above the work material mounting plate cooperates with the intermittent transfer device to transfer the work material in the processing advance direction, and is reciprocatingly movable up and down to resiliently press the work material during time when a transfer is stopped; and characterized in that it comprises an upper planar electrode which is disposed above the work material mounting plate so as to be reciprocatingly movable up and down and has an electrode surface with a width not less than a transfer width of feed dogs of the intermittent transfer device in the processing advance direction, and a lower planar electrode which is disposed and secured in the bed section below the work material mounting plate and has an electrode surface flush with an upper surface of the work material mounting plate and is opposed to the electrode surface of the upper electrode, wherein in a state where the work material is held between the electrode surface of the upper planar electrode and the electrode surface of the lower planar electrode by moving down the upper planar electrode during the time when the transfer by the intermittent transfer device is stopped, the overlapped portions of the fiber cloth are continuously bonded together by allowing the thermoplastic resin tape to melt under high frequency dielectric heating by applying high frequency power between a pair of the upper and lower planar electrodes, wherein the intermittent transfer device comprises the feed dogs disposed in slot-like elongated holes formed in the work material mounting plate, and a feed dogs drive mechanism which causes synthetic circular movement of the feed dogs in vertical and horizontal directions in the slot-like elongated holes, wherein the presser foot serves as the upper planar electrode.