A cationic polyurethane resin aqueous dispersion wherein a cationic polyurethane resin (B) including a structural unit (A) represented by the following general formula (I) is dispersed in aqueous medium, and the content of a cationic amino group of the structural unit (A) in the cationic polyurethane resin (B) is 0.005 to 1.5 equivalents/kg. (In the formula, R1 represents an alkylene group which may include an alicyclic structure, a residue of bivalent phenol or polyoxyalkylene group, R2 and R3 each independently represents an alkyl group which may include an alicyclic structure, and R4 represents a hydrogen atom or a residue of the quaternizing agent which is introduced by the quaternizing reaction, and X− represents an anionic counter ion.)