To provide a device for measuring an electromagnetic disturbing wave for precisely measuring the electromagnetic wave noise of a digital circuit being an object to be measured.

A clock signal is inputted from a digital circuit mounted on a print wiring board 1 to a clock measuring probe 2, and a magnetic field signal generated from the print wiring board 1 is detected by a magnetic field sensor 3. In this case, the magnetic field sensor 3 is moved to a designated position on the print wiring board 1 by a detecting position moving part 4, and the clock signal from the clock measuring probe 2 and the magnetic field signal from the magnetic field sensor 3 are quantized by digitizers 5 and 6, and the frequency components of the magnetic field signal are analyzed for every one time of clock cycle within a designated measuring time by a frequency analyzing part 7, based on the quantized clock signal and magnetic field signal. Then the frequency component pattern of the analyzed magnetic field signal is classified and evaluated by a similarity evaluating part 8 according to the similarity, and the frequency component pattern is stored in a storage part 10.