PURPOSE: To provide a knitting machine easily operated and having little troubles by installing a means for fixing a position of a middle plate piece, which is strained by a spring action between a needle canal bed and the lower side of a control plate piece bed, and the needle canal bed and/or the control plate piece bed to position the middle plate piece in the longitudinal direction.

CONSTITUTION: One end of a middle plate piece 26 is laid on a joint part 16 and the other end is folded to form a hair pin shape. The middle plate piece is supported on the bed 14 of a needle canal 10 by the bent leg 28 and strained between the bed 14 and the lower side 31 of a control board piece bed 30. The middle plate piece 26 is capable of being positioned. A leg part 32 facing to the bed 30 has a perpendicularly running gap and one of three extended needles 36 is neatly housed in the gap ranging the whole of the needle bed.