To provide a metal decorative electronic key which exerts high-quality design by decorating a key body with metals, and ensures sufficient radio communication performance even after the decoration with the metals.

A portable machine 3 is a vehicle key for use in operating a vehicle via a hands-free system, and therefore it can transmit an ID code inherent in itself by radio. In order to ensure the high-quality design of the portable machine 3, the decorative metals 26, 29 formed of metallic materials such as aluminum, for instance, are applied to both front and rear surfaces of a case 21 of the portable machine 3. The upper-side decorative metal 26 has formed therein a plurality of long and slender slits 30a, 30b for partitioning the metal into a plurality of metal pieces. The upper-side decorative metal 26 is composed of the metal pieces which are not continuous to each other but split from each other by the slits 30a, 30b, and therefore it hardly functions as a radio wave shielding member.