Raman spectroscopy is one of the vibrational spectroscopies. Raman spectra of fats inform us of the vibrational states of acylglycerol molecules that reflect chemical structure, physical states, and the microenvironment at the molecular level. One of the great advantages of Raman spectroscopy is that it is less invasive; a sample can be studied in situ using laser light without pretreatment. Taking advantage of this spectroscopy, we investigated the crystalline states of meat fats and developed an in situ method of evaluating the degree of crystallinity and the crystalline polymorphs of fats. This method serves as a basis for such applications as the on-site quality measurement of meat fats and the species-specific detection of pork fat. This review describes the basics of Raman spectral analysis of the crystalline state of fat and its applications to meat products.