To obtain an additive-type spontaneously decomposable resin composition and a spontaneously decomposable molded article having a decomposition rate adjustable with a safe component.

The spontaneously decomposable resin composition is composed of (A) 90-5 wt.% thermoplastic resin, (B) 0.01-1 wt.% coordination compound of a transition metal and (C) 10-95 wt.% wood flour. The composition is used as a molding material. The composition is preferably further compounded with an aromatic ketone, an unsaturated compound having double bond and a compatibilizing agent.