A use time managing method of a semiconductor device may include (1) measuring an amount of accumulated operation time of the semiconductor device and when the amount is reached to a predetermined value, generating a unit storage activation signal; (2) repeating step (1) to generate one or more additional unit storage activation signals, thereby generating a plurality of unit storage activation signals, wherein the predetermined values are different for each repeating step; (3) storing data indicating each occurrence of generating the unit storage activation signals; and (4) detecting use time of the semiconductor device based on the cumulatively stored data.