A gas mask structure including a rear cup body, two cell seats and a front cup body. The rear cup body has an opening facing backward. A top side of front face of the rear cup body is formed with an inlet and a guide way downward extends from the inlet. An inclined outlet is formed on a bottom side of front face of the rear cup body. A check membrane is disposed on front side of the outlet. The cell seats are respectively disposed on two sides of the bottom of the rear cup body for receiving cells therein to provide power for a motor to drive a fan. The front cup body is fixedly disposed on lower side of the front end of the rear cup body. A filter body is positioned in a fixing seat of the front cup body. A cover body is screwed on the fixing seat to fix the filter body therein and tightly hold a second filter body in front of the filter body. An inner face of the fixing seat is formed with a through hole in which the motor and the fan are disposed. The fan serves to generate air flow which is filtered through the second filter body and the filter body and then conducted into the guide way of the rear cup body.