Provided is a method of measuring a degree of degradation/alteration of a lubricating oil, including obtaining dielectric constants or electrostatic capacitances at two or more different frequencies and determining a degradation/alteration state of the lubricating oil based on values of the dielectric constants or the electrostatic capacitances, in which one frequency (H1) of the two or more frequencies is in a range of 1 to 100 Hz, and another frequency (H2) is more than the frequency (H1) and in a range of 10,000 Hz or less. Accordingly, it is possible to provide a method of measuring a degree of degradation/alteration of a lubricating oil and a measuring device therefor, which are capable of measuring a degree of degradation of the lubricating oil easily and precisely and predicting a degradation/alteration mechanism of the lubricating oil.