The invention relates to an armrest locking device for an automobile seat, which comprises a casing, wherein the casing is provided with a casing cavity; an anti-backlash sleeve arranged in the casingcavity, wherein the anti-backlash sleeve is provided with an anti-backlash sleeve cavity; a dial plate arranged in the anti-backlash sleeve cavity, wherein one side of the dial plate is convexly provided with a tooth plate shaft and a spring stop block; an outer tooth plate, wherein an abdicated hole is arranged in the middle part of the outer tooth plate, and an outer rack is arranged below thehole wall of the abdicated hole; a
cam housing, wherein a
cam is arranged on one side thereof; a main shaft, wherein the main shaft passes through the casing, the anti-backlash sleeve, the dial plate,the abdicated hole and the
cam housing, the device also comprises a tooth plate, a locking spring and a plectrum spring, wherein the middle part of the tooth plate is arranged on the tooth plate shaft, one end of the tooth plate is provided with a top pin, the other end of the tooth plate is provided with a locking pin, and an inner rack is arranged on the outer side of one end of the top pin; the locking spring is arranged in the abdicated hole, one end of the locking spring is embedded in a locking spring embedding groove, and the other end extends to the lower part of a locking pin embedding groove; the plectrum spring is arranged between the spring stop block and the top pin. Locking of the
handrail in a vertical position is realized; the structure is simple, the volume is small, theinstallation is convenient, and the operation force is small; the adjustment precision is low and the strength is high; the shaking gap is reduced.