Abstract: A method of detecting an illegal broadband radio signal, includes receiving, by a reception unit, a surrounding radio signal at a place where an illegal radio signal is to be detected, generating, by a detection unit, reference frequency information by configuring a reference multi-spectrum table, generating, by the detection unit, detection frequency information by configuring a detection multi-spectrum table in such a way as to generate a basic resolution spectrum by extracting the signal of the preset frequency band as basic resolution from a detection radio signal detected in the place, and identifying, by a determination unit, whether a signal intensity value greater than a signal intensity value of the reference multi-spectrum table is present in the detection multi-spectrum table.