A portable hot water supply tank is adapted to be used with a heat source, and includes a water storage unit, a heat exchange unit, and a circulation unit. The water storage unit includes a base member defining a lower water chamber. The heat exchange unit includes a heat exchanger connected to the base member. The circulation unit includes an inlet pipe and an outlet pipe. The heat exchanger is movable relative to the base member between an unfolded position and a folded position. When the heat exchanger is at the first position, water stored in the lower water chamber is drawn into the inlet pipe, flows through the heat exchanger to be heated by the heat source, and eventually flows back to the lower water chamber via the outlet pipe.