To provide a lime soap dispersing agent showing excellent dispersion and removability of a lime soap, a detergent composition and a cleaning agent composition each containing it.

A lime soap dispersing agent is represented by the formula (1); (wherein A is -CO-; R1 is a 2-4C alkylene group; R2 is a 3-4C alkylene group; R3 is a phenylene group, naphthylene group or a biphenylene group; R4 and R5 are each a 2-8C alkylene group; R6 is a phenylene group, a naphthylene group or a biphenylene group which may be substituted with -SO3M or -COOM; X is a 1-4C alkyl group, -R7SO3M, -R8COOM or -C(O)R9 (wherein R7, R8 and R9 are each a 1-4C alkyl); m1 and m2 are each 0 to 25; m1+m2 is 3 to 25; n1, n3 and n6 are each 1 to 40; n2 and n5 are each 0 to 5; and n4 is 1 to 10). A detergent composition contains the lime soap dispersing agent.