An apparatus for twisting welding portions of a segment type stator coils is provided. The welding portions are in a number of layers and inserted into slots of a stator core. The apparatus includes a frame, a number of twisting jigs, and a partition member detachably provided at one of a pair of neighboring twisting jigs, and blocking the coil receiving recesses facing each other of the twisting jigs forming the pair. Each of the twisting jigs is provided for each layer of the stator coils, along a radial direction of the stator core, forming coil receiving recesses along a circumferential direction facing another twisting jig forming a pair, installed on the frame to be rotatable in different directions depending on layers of the stator coils, and is generally ring-shaped.