To provide a moistening water feed device which has a simple construction and can be miniaturized and easily maintained.

A moistening water feed pipe 50 having a plurality of feed water ports 51 directed to the surface of a water fountain roller 20, to which moistening water is applied, is disposed in the direction of the roller 20. A moistening water sump bar 60 is disposed close to the surface of the roller in the width direction thereof to form a water sump 70 between the surface of the roller and the bar 60. The bar 60 has a circular cross section and is provided so as not to rotate. Thus the roller can be easily disposed in parallel to the surface of the roller so that an interval G can be formed between the surface of the roller 20 and the bar 60 in the width direction of the roller, and hence the minimum necessary amount of moistening water is supplied to form a uniform water film over a plate.