A real time clock device for a vehicle may include: a register set provided with a first register, in which second time information is stored, and configured to store Real Time Clock (RTC) data including the time or date; and a data compensation circuit to block an input of a 1 second (1 s) tick to the first register and compensate for a delay time according to the block of the input of the 1 s tick to the first register by an RTC lock signal during a process of transmitting the RTC data to an external device or receiving setting data for the RTC data from the external device.