In the needle selection device on a knitting machine equipped with a Jacqd mechanism, the knitting needles can be brought into various positions in which they are inactive, or are active for knitting, for forming tuck loops and for the transfer of stitches, with the aid of cam means on the carriage. In order to create a needle selection device which is simple in structure and is functionally reliable, blocking levers corresponding in number to the number of needle channels and arranged in accordance with the gauge of the needle separation are provided on a mounting rib extending over the length of the needle bed. At each selection position, on the carriage, there is provided a cam element for pivoting the blocking lever and also an electromagnet controllable for needle selection and having associated therewith a tripping pin for pivoting the blocking lever. The knitting needles, when selected for work, are held in pivoted positions by the respective blocking levers located in blocking positions, either directly or by way of a tilting lever associated with each needle. In order to avoid continuing vibration of the blocking levers following their pivotal movements two permanent magnets may be arranged on the carriage opposite the respective lever arms of each blocking lever.