An optical gas analyzer for measuring the percentage of components in a gas phase by IR absorption, containing a power source, a measuring path containing the gas sample, a photoelectric receiver with an evaluation circuit arranged downstream of it, which receiver detects the IR radiation from the measuring path, and a plurality of filters, which can be introduced one after another into the beam path at a predetermined filter change frequency f, wherein measured signals belonging to the filters are sent by the receiver due to the radiation extinction in the measuring path, is to be improved such that different components in the gas sample can be detected in a simple manner and at good selectivity. To accomplish this object, the receiver is a pyroelectric detector, the evaluation circuit has elements for the evaluation of the voltage signal of the pyroelectric detector, the filter change frequency f is set at a value in the range of the declining branch of the frequency response of the voltage signal, and the pyroelectric detector is selected to be such that the declining branch of the voltage signal has a decline of -20 dB per decade.