A water permeability-imparting agent containing an alkylene oxide adduct (A) of a polyvalent active hydrogen compound represented by Formula (1): R—[O(A1O)m—(CH2CH2O)n—H]1  (1) wherein R represents a residue, after removal of all active hydrogen, of the polyvalent active hydrogen compound; A1O represents a C2 to C4 alkyleneoxy group; m represents an average addition mole number of A1O and is a number of 4 to 50; n represents an average addition mole number of CH2CH2O; and 1 represents a valence and is an integer of 3 to 6, and an average addition mole number ratio between A1O and CH2CH2O in Formula (1), n/m, is 0 to 0.5.