An aluminum chelate-based latent curing agent for curing a thermosetting epoxy resin, in which an aluminum chelate-based curing agent is held in a porous resin obtained by, at the same time, subjecting a polyfunctional isocyanate compound to interfacial polymerization and subjecting a radical polymerizable compound to radical polymerization in the presence of a radical polymerization initiator, and the surface of the aluminum chelate-based latent curing agent has been subjected to inactivation treatment with an alkoxysilane coupling agent. An alkylalkoxysilane is preferred as the alkoxysilane coupling agent. The radical polymerizable compound preferably contains a polyfunctional radical polymerizable compound.