A chemical pump includes a pressure chamber, a partition member for dividing
the
pressure chamber into a cleaning pressure chamber and a discharging pressure chamber,
a filter part disposed on the primary side of the discharging pressure chamber,
and a single drive mechanism. A pair of openings with respective check valves mounted
therein are provided in each of the cleaning and discharging pressure chambers,
and are positioned so as to cause a resist solution to flow only in the +Z direction.
The drive mechanism moves the partition member in the -X direction to cause the
resist solution to be sucked into the cleaning pressure chamber and to cause the
resist solution to be discharged from the discharging pressure chamber. The drive
mechanism moves the partition member in the +X direction to cause the resist solution
to be sucked from the filter part into the discharging pressure chamber and to
cause the resist solution to be supplied from the cleaning pressure chamber to
the filter part so that the sucked resist solution is equal in amount to the supplied
resist solution. This prevents vapor lock and micro-bubble phenomena during the
discharge of the resist solution.