To provide a metallic decoration type electronic key allowing a dead space caused by a slit to be used effectively, the slit having been formed on decoration metal as a countermeasure to cope with worsening of radio communication performance when metallic decoration is provided on the electronic key.

Since a portable machine 3 is the vehicle key used to operate a vehicle by a hand-free system, it can transmit its own inherent ID code by radio communication. Decoration metal pieces 32, 35 made of a metallic material such as, for example, aluminum or the like are attached to both of a surface and a rear surface of a portable machine main body 21 of the portable machine 3 to ensure satisfactory design property of the portable machine 3. Each of the slits 36, 37 having a long and thin shape for dividing the decoration metal pieces 32, 35 into a plurality of metallic pieces is formed in each decoration metal piece 32, 35. An emergency key 22 is stored in the portable machine 3. The slits 36, 37 are used as storage sections in a knob part 23 when storing the emergency key 22 in the portable machine main body 21.