A gas detection device comprises a pump module for drawing in air; a sensor module including a plurality of unit sensors detecting a gas included in the air; a driving module driving the pump module and the sensor module; and a case including a main body mounted to allow at least one among the pump module, the sensor module, and the driving module to be detachable and a cover connected to the main body to allow the at least one among the pump module, the sensor module, and the driving module to be exposed.