A pool apparatus has a surrounding side frame, a tarpaulin and a top portion frame. The surrounding side frame provides a closed geometrical shape defined on the ground after the tarpaulin is surrounded with respect to the ground. The tarpaulin may be constituted by various kinds of waterproof materials. The tarpaulin has a bottom portion, a side portion and a top portion. The shape of the bottom of the tarpaulin corresponds to the closed geometrical shape. The side portion of the tarpaulin connects to the bottom portion and surrounding the surrounding side frame. The top portion of the tarpaulin connects to the side portion of the tarpaulin. The thickness of top portion of the tarpaulin is thicker than the thickness of the other portion s of the tarpaulin. The top portion frame clips the top portion to fix the tarpaulin.
