The evaporative fuel treatment apparatus includes: a fuel tank configured to store fuel for an engine; a sub-tank that communicates with the fuel tank; an adsorber provided inside the sub-tank and configured to adsorb evaporative fuel generated inside at least one of the fuel tank and the sub-tank; a purge mechanism configured to carry out purging for introducing evaporative fuel from the adsorber into the engine; and an in-tank fuel adjustment unit configured to adjust an amount of fuel inside the sub-tank in response to an operating state of the engine, the in-tank fuel adjustment unit including a fuel introduction pump configured to be able to introduce fuel from an outside of the sub-tank to an inside of the sub-tank, the fuel introduction pump being formed of a jet pump configured to be driven by at least part of fuel discharged from the fuel pump.