A gas detection device is disclosed. A gas detection device according to an embodiment of the present invention comprises: a case having a plurality of grooves formed on the outer surface thereof; an inlet coupled to a first groove among the grooves and allowing air to flow into the case; a power button coupled to a second groove among the grooves and turning power on or off; a gas detection unit provided inside the case and sensing gas contained in the introduced air; a light unit coupled to a third groove among the grooves and notifying of an on-off state of the power and whether gas is detected; a battery which supplies power; a beep generation unit which generates a beep when a gas detection signal is received from the gas detection unit; and a power switch which performs an on-off operation for supplying power by means of the power button, wherein at least one of the inlet, the power button, and the light unit is coupled to the grooves in a recessed form, the battery, the beep generation unit, and the power switch are provided inside the case, and the case may be formed in a small spherical shape such that an operator can carry and move same in the palm of his/her hand.