The present invention provides an aqueous curable composition comprising (A) a compound comprising all or some primary amino groups and/or secondary amino groups optionally neutralized with a Brønsted acid, and (B) a crosslinking agent, the crosslinking agent being a compound having an (N-alkyl-N-(2-acylacyl)amino)alkyloxycarbonylamino group represented by General Formula (I)
wherein R
1
, R
2
and R
3
are each independently a hydrogen atom or C
1-7
alkyl group, R
4
and R
5
are each independently a hydrogen atom or C
1-16
organic group, and Y is a straight C
1-6
alkylene group optionally substituted with a C
1-6
organic group as a substituent.