Provided is an apparatus for detecting microorganisms, including: a sample accommodation container having an accommodation space in which a measurement sample in which a number of living microorganisms is to be counted is accommodated; an electrode portion installed at the sample accommodation container so as to apply electrical stimulation to the microorganisms of the sample accommodated in the accommodation space; a current applying control portion that is capable of controlling a current applied by the electrode portion; and an image processor that captures an image of the sample accommodated in the sample accommodation container and counts the number of living microorganisms. Accordingly, the number of living microorganisms can be easily identified by electrically stimulating the living microorganisms, and by comparing an image of the living microorganisms generated before electrical stimulation is applied to the living microorganisms with an image of the living microorganisms generated after electrical stimulation is applied to the living microorganisms, the number of living microorganisms can be easily measured.