A high-speed multi-stage voltage comparator is provided. The multi-stage voltage comparator is configured to eliminate offset from outputs of preamplifiers through respective offset-cancellation switches, and to reset the outputs of the preamplifiers through respective reset switches to reduce an output recovery time. Thus, the multi-stage voltage comparator operates with high accuracy and at a high speed, so that it can be usefully applied to an analog-to-digital converter (ADC), and particularly, a high-speed successive approximation register ADC (SAR ADC).