Vibrational microscopy (Raman microscopy and infrared microscopy), which observes molecular vibrations, gives us the information of molecular species without staining because the observed signals are originated from intrinsic molecules of a cell. However, infrared radiation is absorbed with water, and the long wavelength (3-10 μm) limits the spatial resolution to several micrometers. Spontaneous emission of Raman scattering is quite feeble, and the Raman scattering often overlaps with one-photon fluorescence from a specimen. Coherent anti-Stokes Raman scattering (CARS) microscopy, which is one of the nonlinear Raman microscopy, is a method to overcome those problems. In this review, present system of CARS microscopy, the methods of background rejection, and applications are introduced.