This paper proposes a variable-focus lens with 1-kHz bandwidth. The lens transforms its shape rapidly using the liquid pressure generated by a piezo stack actuator. This mechanism also includes a built-in motion amplifier with high bandwidth to compensate for the short working range of the piezo stack actuator. Prototypes have been developed to validate the proposed design. A 1-kHz bandwidth of the lenses was confirmed by measuring the frequency responses. Refractive power ranging from -1/167 to 1/129 mm-1 and a maximum resolution of 12.3 cycles/mm were attained.