Photoacoustic gas sensor having a light pulse emitter, a microphone in a reference gas housing having a reference gas, and a sample gas housing to be filled with a gas to be analyzed. A wall separates the sample gas housing from the reference gas housing, and has a transparent region that is transparent to light within a frequency range of emitted light pulses. Remaining inner walls of the sample gas housing have a reflecting surface that reflect light pulses emitted by the emitter so that a portion of the light pulses not absorbed by the gas to be analyzed pass through the transparent region into the reference gas volume. The microphone generates a sensor signal indicating information on an acoustic wave caused by the light pulses interacting with the reference gas after crossing the gas to be analyzed.