A liquid coating system according to the present invention comprises, a liquid supply source, a nozzle having an inlet communicating with the liquid supply source and a substantially linear liquid discharge portion, a pressure feed unit for feeding the liquid under pressure from the liquid supply source to the nozzle by means of compressed gas, a spin chuck for fixedly supporting a semiconductor wafer, an up-and-down cylinder for causing the liquid discharge portion of the nozzle to closely face the wafer on the spin chuck, and a rotating mechanism for rotating the spin chuck. The nozzle includes a liquid reservoir, in which the liquid supplied from the liquid supply source is collected, and a large number of small passages communicating with the liquid reservoir. The liquid coating system further comprises an air operation valve disposed in a communication passage between the inlet of the nozzle and the liquid supply source and used to reduce the pressure of the liquid fed under pressure to the liquid reservoir.