A preparative liquid chromatograph includes a liquid feeding pump (2) that feeds a mobile phase, an injector (4) that injects a sample into the mobile phase at a downstream of the liquid feeding pump (2), a separation column (6) for separating components in the sample injected into the mobile phase by the injector (4) at a downstream of the injector (4), and an eluate fractionator (8) configured to divide a flow of the eluate from the separation column (6) into a flow of a minute flow rate and another flow at a downstream of the separation column (6) and to extract at least a part of an eluate that forms the flow of a minute flow rate into an fractionation container (22).