To improve the heat efficiency of whole equipment without impairing the effect of a known invention by further improving the known invention (published unexamined application No. 2006-141786 bulletin) related to heat exchange in a continuous washing machine.

A heat exchanger 14 for a washing/spin-drying machine is installed in a linen factory, fresh water (an arrow (a)) is heated to warm water using waste water (an arrow ) from a first washing tub of this continuous washing machine 1, and the warm water is stored in a warm water tank 15 and supplied to the washing/spin-drying machine 5 as necessary. This constitution can save the heating requirement to be given to the washing/spin-drying machine so as to provide an energy saving effect. The warm water stored in the warm water tank 15 can be fed to a machine other than the washing/spin-drying machine.