A carboxy group-containing aqueous resin composition comprising a carboxy group-containing aqueous resin and a polycarbodiimide compound (X) represented by the following general formula : wherein R 1 represents a residue obtained by removing a functional group capable of reacting with an isocyanate from a hydrophilic compound having the functional group capable of reacting with an isocyanate; R 2 represents a divalent residue obtained by removing isocyanate groups from a diisocyanate compound; R 3 represents a divalent residue obtained by removing hydroxy groups from a glycol compound; X represents a group to be formed through a reaction between the hydrophilic compound and the diisocyanate compound; n1 represents a number of 1 to 10; n2 represents a number of 1 to 10; m represents a number of 1 to 5; and plural R 1 's may be the same or different and plural R 2 's may be the same or different, wherein the glycol compound is at least one selected from the group consisting of ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol and wherein the hydrophilic compound is at least one selected from the group consisting of compounds represented by the following general formulae and : R 4 O-(CH 2 -CHR 5 -O) p -H wherein R 4 is an alkyl group having 1 carbon atom; R 5 is a hydrogen atom or a methyl group; and p is an integer of 4 to 30, (R 6 ) 2 -N-R 7 -OH wherein R 6 is an alkyl group selected from the group consisting of an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, a n-pentyl group, a n-hexyl group, and a cyclohexyl group, and R 7 is an alkylene group having 1 to 10 carbon atoms or a polyoxyalkylene group. wherein R 1 represents a residue obtained by removing a functional group capable of reacting with an isocyanate from a hydrophilic compound having the functional group capable of reacting with an isocyanate; R 2 represents a divalent residue obtained by removing isocyanate groups from a diisocyanate compound; R 3 represents a divalent residue obtained by removing hydroxy groups from a glycol compound; X represents a group to be formed through a reaction between the hydrophilic compound and the diisocyanate compound; n1 represents a number of 1 to 10; n2 represents a number of 1 to 10; m represents a number of 1 to 5; and plural R 1 's may be the same or different and plural R 2 's may be the same or different, wherein the glycol compound is at least one selected from the group consisting of ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol and wherein the hydrophilic compound is at least one selected from the group consisting of compounds represented by the following general formulae and : R 4 O-(CH 2 -CHR 5 -O) p -H wherein R 4 is an alkyl group having 1 carbon atom; R 5 is a hydrogen atom or a methyl group; and p is an integer of 4 to 30, (R 6 ) 2 -N-R 7 -OH wherein R 6 is an alkyl group selected from the group consisting of an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group, a n-pentyl group, a n-hexyl group, and a cyclohexyl group, and R 7 is an alkylene group having 1 to 10 carbon atoms or a polyoxyalkylene group. <EOS>