Provided is an apparatus and method for transmitting/receiving time information in a mobile communication system. In a method for calculating a current time in the mobile communication system, time information is received from a base station. Date information and parameters for calculation of time are obtained on the basis of the received time information. A lapse time length from a reference time is calculated on the basis of the parameters. A current time is calculated using the calculated lapse time length and the date information. The time information is periodically transmitted and received using the idle frame of an idle state and the stealing flag of a normal burst contained in a BCCH.