A flatbed knitting machine equipped with sinker devices, the flatbed knitting machine accommodates knitting needles in needle grooves formed between needle plates (7, 27) arranged in line on needle beds (4, 5), and has sinker devices which are arranged between the knitting needles adjacent at a side of a leading end of the needle bed (4, 5), each of which has a movable sinker (10, 30) and a fixed sinker, arranged in line, the movable sinker (10, 30) operating in cooperation with the knitting needle when a hook of the knitting needle makes a fabric which is knitted by advancing the hook to a needle bed gap and by retreating the hook from there, and the fixed sinker supporting a stitch deciding part being capable for suspending a sinker loop, and a wire rod which functions as a top tooth, when a stitch is knitted, the movable sinker (10, 30), being accommodated in a thin thickness part which is provided on the needle plate and capable of rocking, and being driven by a sinker jack being capable of advancing to and retreating from the needle bed gap, and provided with: a rocking support receive part supported by a rocking support part which is formed on the thin thickness part; a function arm extending from the rocking support receive part towards the needle bed gap and has a yarn receive part at a leading end; a drive arm extending from the rocking support receive part in a direction away from the needle bed gap and has a drive receive part at a leading end; characterized in that a spring biasing the function arm in a rocking direction towards the needle bed gap so that the yarn receive part is capable of pressing a stitch, and the movable sinker being driven by a sinker jack capable of advancing to and retreating from the needle bed gap, and the sinker jack being provided with: a base part accommodated in the needle groove, having a width for being capable of advancing and retreating therein, and being disposed above the knitting needle; a wide width part is provided above the base part, and having a width widening to a side on which the movable sinker (10, 30) is accommodated; a drive part provided in a vicinity of a leading end of the wide width part, which is close to the needle bed gap, and driving the drive receive part of the drive arm of the movable sinker (10, 30) by one of a direction advancing to and a direction of retreating from the needle bed gap, and causing the function arm to rock in a direction of retreating from the needle bed gap against the pressure of the spring; and a leading end part provided on the wide width part at a leading end side, having a width for being capable of advancing to and retreating from the needle bed gap in the needle grooves when accommodated therein, and being arranged above the knitting needle; and wherein at least a part of a side surface of the movable sinker (10, 30) is supported by the leading end part of the sinker jack at a side of the needle groove. a rocking support receive part supported by a rocking support part which is formed on the thin thickness part; a function arm extending from the rocking support receive part towards the needle bed gap and has a yarn receive part at a leading end; a drive arm extending from the rocking support receive part in a direction away from the needle bed gap and has a drive receive part at a leading end; characterized in that a spring biasing the function arm in a rocking direction towards the needle bed gap so that the yarn receive part is capable of pressing a stitch, and the movable sinker being driven by a sinker jack capable of advancing to and retreating from the needle bed gap, and a base part accommodated in the needle groove, having a width for being capable of advancing and retreating therein, and being disposed above the knitting needle; a wide width part is provided above the base part, and having a width widening to a side on which the movable sinker (10, 30) is accommodated; a drive part provided in a vicinity of a leading end of the wide width part, which is close to the needle bed gap, and driving the drive receive part of the drive arm of the movable sinker (10, 30) by one of a direction advancing to and a direction of retreating from the needle bed gap, and causing the function arm to rock in a direction of retreating from the needle bed gap against the pressure of the spring; and a leading end part provided on the wide width part at a leading end side, having a width for being capable of advancing to and retreating from the needle bed gap in the needle grooves when accommodated therein, and being arranged above the knitting needle; and