An apparatus for detecting a particle is disclosed. The apparatus for detecting a particle in a fluid in accordance with an embodiment of the present invention can include a first light source, which emits a first beam having a wavelength of a particular band toward the fluid, a second light source, which emits a second beam having a wavelength of a band that is different from that of the first beam, a first dichroic mirror, which is placed between the fluid and the first light source and allows the first beam to permeate and reflect the second beam toward the fluid, and a detecting unit, which detects a dispersed beam of the first beam and the second beam in the fluid. An embodiment of the invention can improve the reliability of detection by detecting a particle using a beam that has an optimal permeability according to the type of solution.