A resin material of high strength and high voltage equipment capable of improving the reliability by using the resin material, the resin material being a hardened product including fine particles and resin ingredients, in which the fine particles have hydrophobic groups on the surface and have a particle diameter of 200 nm or less, the resin ingredients have hydrophilic groups on the side chains, and the fine particles form a plurality of linear aggregates inside the resin, thereby forming a dendritic structure.