PURPOSE: To reduce weight of a circular knitting machine by reducing height of a needle cylinder and thereby to reduce inertia at the time of running in a selection device of a latch needle.

CONSTITUTION: Needles 4 are guided by needle jacks 3 on which selecting jacks 5 are swingably provided. The selecting jacks 5 are equipped with two guiding butts 51, 52 which are alternately engaged with cam paths to guide the needles in the knitting or non-knitting positions. Means acting on the swinging selecting jacks are arranged in relation to the height of an arch section of a cylinder where the needles are simultaneously inserted in both the upper and lower needle jacks.