There is provided an aging diagnostic device including: a reference ring oscillator (101) that constitutes a ring oscillator using an odd-numbered plurality of logic gates constituted using a CMOS circuit; a test ring oscillator (102) that constitutes a ring oscillator using an odd-numbered plurality of logic gates having the same configuration as that of the logic gate; a load unit (104) that inputs a load signal to the test ring oscillator (102); a control unit (105) that simultaneously inputs a control signal instructing a start of oscillation of the reference ring oscillator (101) and the test ring oscillator (102) to the reference ring oscillator (101) and the test ring oscillator (102); and a comparison unit (103) that compares differences in the amount of movement of pulses within the reference ring oscillator (101) and the test ring oscillator (102), respectively, in the same time.