A method and module for a mobile terminal that enable A user to freely create an offset clock and reset the time on the offset clock are disclosed. The clock operation method includes: generating a time offset value using a reference time signal from an internal clock and using a time gap value input by a user while at least one offset clock created in advance is in operation on the basis of the reference time signal; creating a new offset clock using the generated time offset value; and displaying the time of the created new offset clock. As a result, the user can operate a plurality of personalized offset clocks, each of which keeps time relative to a reference clock.