To provide a prepaid type portable telephone set which is compact and easy to carry, further, can be easily purchased without contract and moreover, can be easily collected and recycled after use without wasting resources.

A prepaid type portable telephone set 1 is composed of a telephone set body 2, which is formed in the rectangular shape of thin plate, and a cover body 3 provided attachably and detachably on the telephone set body 2 so as to freely slide up and down and a prepaid memory device servicable just for prescribed time is provided inside the telephone set body 2.