A data processing system including a shared resource, a first data processing device configured to generate a first resource request signal requesting the shared resource, a second data processing device configured to generate a second resource request signal requesting the shared resource, and a resource manager master configured to receive the first resource request signal and the second resource request signal, check a state of the shared resource, determine whether the first resource request signal or the second resource request signal is received earlier, and output a grant signal to the first data processing devices and a rejection signal to the second data processing device when the first resource request signal is received earlier than the second resource request signal. The first data processing device processes data using the shared resource according to the grant signal.