The present invention herein provide a cleaning agent which comprises (A) an aqueous solution or an aqueous dispersion containing a linear poly(meth)acrylamide having an average molecular weight of not less than 5×106 as determined according to the intrinsic viscosity-determining technique in a concentration ranging from 0.0001 to 0.01% by mass; (B) a poly(hexamethylene-biguanide) hydrochloride represented by the following general formula (1); and (C) at least one compound selected from the group consisting of propylene glycol, dipropylene glycol, tripropylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and ethers of ethylene glycol and propylene glycol with alcohols each having 1 to 3 carbon atoms, and esters thereof with fatty acids each having 1 to 3 carbon atoms, glycine and taurine: [—(CH2)m—NH—C(NH)—NH—C(NH)—NH—(CH2)n—]p.HCl  General Formula (1) wherein m and n each represent an integer ranging from 2 to 5 and p is an integer ranging from 5 to 16.