To provide a cross-sectional observation method of cosmetics which allows cross-sectional observation at a desired position regarding the cross-sectional observation method of the cosmetics for observing a cross-section of the cosmetics by using a scan type electron microscope, etc.

A cross-sectional observation method of cosmetics has: a sample preparation process S1 of arranging the cosmetics in a sample holder to prepare a sample; a freezing process S2 of freezing the sample; a cutting process S3 of processing the frozen sample by a focused ion beam to form a cut surface on the sample; and a cut surface image processing process S4 of generating a cut surface image of the cut surface by using a scan type electron microscope. In addition, shield processing is performed to the sample frozen in the freezing process S2 as maintaining freezing environment, the cutting process S3 and the cut surface image processing process S4 are executed as maintaining the freezing environment. In this case, any of artificial skin, resin tape, or the skin is used as a support base, and the frozen sample is arranged in a shield member at a vacuum state or filled with inert gas in the shield processing.