To provide a portable transmitter which gives a sure notice of the fraudulent operation of taking out an element for electronic authentication, without disassembly of a housing, when the fraudulent operation is performed.

In this portable transmitter, the element 4 for electronic authentication is fixed in the housing 3 which has upper and lower covers 1 and 2 disconnectably connected together. The element 4 is fixed in the state of being housed in a storage space 6 which is formed in a floating-island shape on the inner wall surface of either of the upper and lower covers 1 and 2 and formed of a tubular portion 5 formed in such a manner that a fracture surface brought about by a swing destruction operation can advance to the surface of the cover.