Provided are a resin composition for forming a varistor and a varistor capable of increasing freedom in the design of substrates, ICs, or electronics. The resin composition for forming a varistor includes (A) an epoxy resin, (B) a curing agent, (C) carbon nanotubes, and (D) a dispersant. The (C) carbon nanotubes may be single-walled carbon nanotubes, multi-walled carbon nanotubes, or a combination thereof. The (D) dispersant includes a polyalkyl oxide surfactant. The polyalkyl oxide surfactant has a polyalkyl ether skeleton in the molecule.