Portable instrument for data storage medium

A portable instrument for a data storage medium which is used for a non-contact personal identification system comprising a data storage medium and an external processing unit for exchanging information with the data storage medium or transmitting and receiving data to and from the storage medium,

• wherein the data storage medium is composed of data storage means and an antenna coil which are electrically connected to each other, being mounted on a base material and is made in the form of a non-contact tag externally sealed with a resin,
• wherein the tag is secured, at a securing position, to the surface of a transparent cover for covering a time display surface of a wristwatch, the securing position being such a position that allows recognition of the time displayed by time displaying means, wherein the transparent cover has a recess at said tag securing position and the tag is removably fitted in and secured to the recess, and wherein the transparent cover is for an analog wristwatch and has a size falling in a range which allows recognition of indications presented by a minute hand and a hour hand.