The invention relates to a control method of an autosampler. The autosampler utilizes a metering pump to suck a liquid sample and injects the liquid sample into an analysis flow path by switching a multi-way valve. The control method comprises driving a metering pump to suck a liquid sample, waiting for a predetermined time, and switching the multi-way valve to make the metering pump communicate with the analysis flow path. The invention also relates to a control device of an autosampler.