PURPOSE: To efficiently remove organic halogen substances dissolved in water by forming a leading-in inlet and a leading-out outlet to run an aqueous solution containing volatile dissolved organic substances in a space between a hollow fiber membrane and a container and forming a gas discharging outlet to discharge a gas in a hollow part of the hollow fiber membrane.

CONSTITUTION: An aqueous solution containing volatile organic substances is led through a leading-in inlet 12, passes an apparatus 3 for removal of organic substances volatile in water and a hollow fiber membrane module 4 and flows out of a faucet, wherein the removal apparatus 3 is composed of an absorbent 2, a module 6 for removal of organic substances dissolved in water, and a pressure decreasing apparatus 7. The module 6 for removal of organic substances dissolved in water has diaphragms to separate spaces communicating with the hollow parts of hollow fiber membranes and spaces communicating with the outer surfaces of the hollow fiber membranes and space are partitioned by the outer surfaces of the hollow fiber membranes and the inner wall face of a container and an inlet and an outlet to run an aqueous solution containing dissolved organic substances, a discharging outlet to discharge gas in the spaces and a gas suction inlet to take in air out of the container, and a gas sucking and discharging mouth to suck and discharge a gas in the hollow parts of the hollow fiber membranes are formed in the module.