Automatic alarming gate

The utility model relates to an automatic alarming gate, which includes a control box (1) and an infrared distance measurement sensor (8), wherein the infrared distance measurement sensor (8) is mounted on the inner surface of a door leaf, with a probe facing to the rear side directly; a magnetic control switch (2), a battery box (3) arranged at the edge of a key hole, a controller (4), an amplifier (5), and a speaker (6) are arranged inside the control box (1); moreover, a magnet (7) matched with the magnetic control switch (2) is mounted on a key handle. The controller (4) is a singlechip minimum system, the magnetic control switch (2) and the infrared distance measurement sensor (8) are connected with an input interface of the controller (4), the amplifier (5) is connected with an output interface of the controller (4), and the output of the amplifier (5) is connected with the speaker (6). As a good helper necessary for home security, the automatic alarming gate has strong practicality, so that thieves can