To provide a composition for a high voltage electrical insulation showing good water-proof tree, especially bowtightly.

The composition for electrical insulation consists of 1 to 80 parts by weight of polyethylene or ethylene copolymer or a mixture of these, 1 to 20 parts by weight of elastomer having a styrene component in its molecule, and 0.1 to 2 pants by weight of hydrophilic polymer capable of restraining a local moisture concentration. An electric wire and cable use the composition as an insulating layer. A copolymer of styrene, maleic anhydride and allyl ether, or a polyethylene glycol with a molecular weight of 10,000 or more is used as the hydrophilic polymer.