Quasi-biennial oscillations belong to the most prominent mid-term periodicities with a durationshorter than 11-year cycle and longer than solar rotation. Sunspot number and area, intensity ofcoronal green line, solar radio flux, number of Hαflares, solar wind velocity, interplanetary mag-netic field, as well as cosmic rays exhibit quasi-biennial oscillations in their temporal changes.However it was deeply studied, the source of the quasi-biennial oscillations is unrevealed yet.One of the concepts relates quasi-biennial oscillations toa high-frequency component of the solardynamo functioning within the Sun’s interior. Here, we propose as the origin of quasi-biennialoscillations of cosmic rays solar differential rotation.We use 27-day averaged data of cosmic rays measured by Oulu neutron monitor and solar ra-dio flux being a proxy of the level of solar activity. We compute wawelet coherence (WTC) in1966-2019. Figure 1 shows that the shorter periodicities characteristic for QBO appeared clearlyaround 1971-1973, 1990-1993 and 1997-2003. The longest remained practically in the eightiesand nineties.