To make content irreproducible in a recording device after a set
expiration time, the recording device has a read/write unit for reading
and writing data on a recording unit, the read/write unit having electric
power supplied from an external power source, a clock containing a
built-in battery, an input/output interface for inputting data from
outside and outputting data to outside, and a controller for controlling
the read/write unit and the input/output interface. The recording medium
includes an ordinary data area for writing ordinary data and an
expiration time data area for writing an expiration time of ordinary
data. The controller prevents ordinary data written in the ordinary data
area from being output to outside when the expiration time written in the
expiration time area has passed a time limit calculated by the clock.