A multilayer highTcsuperconducting field‐effect transistor‐like structure was made from ultrathin YBa2Cu3O7−xfilms. An epitaxially grown dielectric SrTiO3insulation layer, which had a forward bias breakdown voltage of about 20 V, allowed an electric field induced change in the channel layer of 1.25×1013carrier/cm2per volt of the gate voltage. A significant modulation of the normal state and superconducting properties was observed in samples with YBa2Cu3O7−xchannel layers of a few unit cells thick. By applying gate voltage of different polarities,Tcwas both suppressed and enhanced by ∼1 K. The resistance was modulated by as much as 20% in the normal state and by over 1500% near the zero resistance temperature.