A processing apparatus includes an FPGA unit connected to an oscillator configured to output a first clock, wherein the FPGA unit includes: a PLL circuit configured to output a second clock with a frequency of a predetermined ratio with respect to a frequency of the first clock and configured to output a lock signal (detection signal); an input and output monitoring unit configured to detect a ratio between the frequencies of the first clock and the second clock, compare the detected ratio with the predetermined ratio, and output an abnormal signal when the detected ratio does not coincide with the predetermined ratio; and an initialization unit configured to output a reset signal when the input and output monitoring unit outputs the abnormal signal and configured to output the reset signal when the PLL circuit outputs the lock signal.