A gas concentration measurement device measures a gas concentration based on an absorbance of sample gas in a region between a light source that emits infrared light and a detector that detects the infrared light. The gas concentration measurement device includes a rotating member, first and second band pass filters on the rotating member, and a rotational driver. The first and second band pass filters are located on a pair of planes that intersect each other. The rotational driver rotates the rotating member around the rotating shaft to switch between a first state, in which the infrared light from the light source is transmitted through the first band pass filter, and a second state, in which the infrared light from the light source is transmitted through the second band pass filter.