The most important function of skin is to form a barrier between the inside of human and the external environment. The stratum corneum, the outermost layer of the skin, is at the forefront of this barrier and prevents excessive water loss and the entry of harmful substances from the environment. To perform the barrier function, the stratum corneum forms a characteristic structure. The stratum corneum is an air-liquid interface barrier on the body surface and the result of keratinization of the epidermis. The stratum corneum is composed of the protein rich materials of the corneocytes and intercorneocyte water impermeable lipid lamellae. Corneocytes are wrapped with cornified cell envelope and corneocyte lipid envelope. The lipid envelope contains a complex mixture of polar and nonpolar lipids in its extracellular spaces. Therefore, the key components of the skin barrier are lipids and proteins. In this review article, we summarize the formation and structure of a cornified cell envelope and corneocyte lipid envelope as proteins and lipids of skin barrier.