A multiport valve used for a water quality analyzer is provided with: a valve head having a plurality of ports for receiving pipings for connections therebetween, the ports being provided on an outer surface of the valve head, the valve head including a connection surface in which ends of flow paths communicating with the respective ports are arranged in the same plane, the valve head being made of a resin material having corrosion resistance against a chemical used in the water quality analyzer; a rotor having a flat surface provided with a groove for switching a connection state between the ends of the flow paths arranged on the connection surface, the flat surface being arranged so as to face the connection surface; and a drive mechanism configured to rotate the rotor.