To provide a water treatment apparatus capable of treating a large quantity of water to be treated at a high speed.

The water treatment apparatus is equipped with: a spiral type separation device provided with a spiral flow passage composed of a sealed passage wound so as to be a spiral shape in the range of 0 to <40° to the horizontal direction; and a hollow fiber membrane type filtration device at the downstream of the spiral type separation device. In the spiral type separation device, the spiral flow passage has a cross-sectional rectangular shape surrounded by the upper and lower flat walls, the inner circumferential wall and the outer circumferential wall, the edge part on the central side of the spiral flow passage is used as a treatment liquid inlet, the edge part of the outermost circumferential part of the spiral flow passage is used as a treated liquid outlet, a capture plate for removal matter in a treatment liquid is installed freely attachably/detachably along the inside face of the inner circumferential wall and the outer circumferential wall of the spiral flow passage, and the capture plate is provided with a capture part which can achieve the capturing.