To provide an energy ray curing type elastomer composition with high flame-retardancy having sufficiently low hardness and maintaining rubber characteristics such as flexibility, expansion/contraction property and elasticity.

The energy ray curing type elastomer composition includes (A) an energy ray curing type oligomer having (meth)acryloyl, (B) an energy ray curing type monomer having a (meth)acryloyl group and containing at least one selected from isocyanurate groups, phosphazene groups and bromide and (C) a polythiol compound having 2-6 mercapto groups in the molecule. The energy ray curing type elastomer composition contains 10-50 pts.mass of the component (B) relative to 100 pts.mass of the component (A) and the functional group number ratio of the (meth)acryloyl group in the energy ray curing type elastomer composition and the mercapto group in the component (C) is 100:0.3-100:n (n is the number of the mercapto group in one molecule of the polythiol compound).