The present invention relates to a method for detecting food poisoning bacteria, and more particularly, to a method for rapidly and quantitatively isolating food poisoning bacteria contents which contaminate food and the like. The method according to the present invention is characterized by including the steps of: introducing magnetic nanoparticles which can bind to bacteria into a sample for measuring the bacteria so as to bind the magnetic nanoparticles to the bacteria; isolating the magnetic nanoparticles; passing the nanoparticles which are isolated by using magnetism through a solution having high viscosity so as to separate the magnetic nanoparticles to which bacteria are bound from magnetic nanoparticles to which no bacteria are bound; and quantifying the magnetic nanoparticles to which bacteria are bound.