The present invention relates to a composition for detecting microbial contamination comprising a preparation for detecting nucleases, and a use thereof. A probe for measuring nucleic acid double-stranded nucleases, according to the present invention, may detect the comprehensive nucleic acid degradation capability of nucleases, whereby it is possible to quickly and precisely detect and quantify live microorganisms in a sample in a simple manner. Moreover, since the probe of the present invention is characterized in that signals of fluorescence consistently increase; is capable of measuring live microorganisms; and consists of a double-stranded nucleic acid, the probe is excellent for storage in a kit or a cartridge. As such, it is expected that the probe of the present invention may be used to easily and simply measure and compare the degree of contamination of microorganisms in an environment.