Abstract: A time synchronization apparatus and a method using a GPS (Global Positioning System) of a satellite. An oscillator oscillates a frequency required for a Global Positioning System of a satellite. A counter generates an internal 1 pps by counting the oscillating frequency of the oscillator. A comparator outputs a phase difference by comparing the phase of the internal 1 pps outputted from the counter and the phase of the 1 pps signal received by the Global Positioning System. A buffer stores the phase difference comparison output of the comparator. A first controller corrects the phase difference of the internal 1 pps outputted from the counter. A second controller corrects an oscillating frequency outputted from the oscillator and the phase difference of the output frequency of the first controller.