This investigation was carried out in order to clarify experimentally fatigue crack propagation in steels under stationary random fully reversed tension-compression loading. Sine wave loads and random loads with different power spectra were applied to S20C-equivalent and S35C-equivalent steel specimens under displacement-controlled and load-controlled loading. The fundamental properties of fatigue crack propagation, the effect of power spectra, and the threshold for fatigue crack propagation in steels under random loading were clarified.