In a knitting member selection actuator (1) of a knitting machine, there is provided between a pair of yokes a magnetic property means (35a, 35b, 45a, 55a, 55b) for making a magnetic reluctance between the confronting yokes (32a, 32b, 42a, 42b, 52a, 52b) of an uncontrolled attraction region (7, 8, 9) larger than a magnetic reluctance between the yokes of the uncontrolled attraction region and the knitting member attracted to attraction surfaces and also smaller than a magnetic reluctance between the yokes of the uncontrolled attraction region and attraction surfaces of the adjacent controlled attraction region (5, 6).