The nitrous oxide gas monitor is used for real-time monitoring of residual gases in the environment in various medical supplies, medical consumables production units, pharmaceutical factories, disinfection supply centers, or operating rooms, with an alarm for concentration exceeding the standard. This gas monitor can monitor the concentration of residual gases in the room air. When the concentration reaches or exceeds the preset alarm threshold, the monitor will emit an audible and visual alarm. It can be linked with gas remote alarm controllers or exhaust facilities such as fans to timely remind operators to take safety measures to prevent explosions and poisoning accidents, thereby ensuring the safety of life and property, It is a safety guarantee for on-site operations using toxic gas sterilization equipment.