A computer apparatus and a resetting method for a real time clock (RTC) of the computer apparatus are provided. The resetting method for the RTC includes: generating a judging result by determining whether the computer apparatus is in an S5 state and determining whether a plurality of pre-determined keys are simultaneously pressed; pulling down a resume reset signal according to the judging result and correspondingly pulling down an operating voltage; pulling down an S5 enabling signal after pulling down the operating voltage for a pre-determined delay time; generating an RTC reset signal for resetting the RTC after pulling down the S5 enabling signal is pulled down.