Belt wheel and window lifter with belt wheel

The belt wheel is provided with a main winding part (2) and an auxiliary winding part (3), the main winding part (2) is provided with an annular main winding groove (23) capable of winding a metal wire (W) between a first flange (21) and a second flange (22), the auxiliary winding part (3) is provided with an auxiliary winding groove (32) capable of winding the metal wire (W) between the second flange (22) and a third flange (31), and the auxiliary winding groove (32) is provided with a closest part (321) and a bent part (322). The third flange (31) has a closest section (321) that is closest to the main winding groove (23) in the radial direction of the main winding groove (23), and a bent section (322) that is bent toward the main winding groove (23) at a portion adjacent to the closest section (321) so as to join the main winding groove (23) at the closest section (321), and the third flange (31) has an auxiliary guide section (311). The auxiliary guide portion (311) extends in the radial direction of the