In accordance with a startup circuit, a capacitive sensor amplification device having the startup circuit, and a startup method for the amplification device, a startup time can be shortened by connecting the high impedance resistor of an amplifier to a predetermined voltage source during startup. The capacitive sensor amplification device includes an amplification unit for amplifying a signal input to the amplification device; and a startup circuit for improving a startup time of the amplification unit, wherein the startup circuit includes a comparator for receiving an output of the amplification unit as a first comparison signal, receiving a preset reference voltage as a second comparison signal, comparing the comparison signals with each other, and outputting a comparison result; and a switch for selecting and outputting one of a first voltage and a second voltage depending on the output of the comparator.