PURPOSE: To provide an adhesive composition particularly improved in adhesion to wet cellulosic products in the adhesion between a cellulosic product and another cellulosic product or of a cellulosic product to other substances such as a nonwoven fabric, or a synthetic resin product, for example, an olefinic sheet or an olefinic film.

CONSTITUTION: The adhesive composition comprises 100 pts.wt. of a rubber thermoplastic block copolymer which is prepared by modifying a rubber thermoplastic block copolymer (styrene-ethylene-butylene-styrene block copolymer) so as to contain at least one carboxyl group in every molecule or to have 1 or more acid value, 5 to 500 pts.wt. of process oil and 50 to 800 pts.wt. of a pressure-sensitive adhesive resin.