Abstract: A unique time generating device is incorporated in a computer which includes a CPU (1), a memory (2) and an I/O device (3). The CPU (1) includes a timer section (4) and an accumulating section (5), and the memory (2) includes a storage section (6) for storing a preset time-measuring period and a renewal section (7) for renewing the time-measuring period. The storage section (6) stores therein a total of time values Tt to be counted over the time-measuring period, which may, for example, be 3,155,692,500.97 seconds corresponding to a 100 year period. The timer section (4) constantly counts the total time value, and the accumulating section (5) calculates an accumulated time Tn progressively incrementing from the zeroth second toward the designated total time value Tt and a subtracted time (Tt-Tn) progressively decrementing from the total time value toward the zeroth second, so as to constantly measure an elapsed time within the preset period.