The piezoelectric pump unit consists of a housing, a piezo anchor, located in the housing, a displacer, located at the front of the housing. The piezo anchor and the displacer are connected. The piezo anchor consists of a rear piezoelectric clamp section, of a piezoelectric extender section and of a front piezoelectric clamp section, connected in series. At least one slider is introduced in the piezoelectric extender section between its front and rear ends. Electric pulses accessing at sections from a control station cause said sections to become fixed alternately inside the housing. Under the effect of electric pulses, the piezoelectric extender section moves the displacer step-by-step in one direction.