Trehalose is a non-reducing disaccharide consisting of two glucose residues. Industrial mass-production of trehalose from starch has been achieved by using enzymatic reactions of maltooligo-syltrehalose synthase and maltooligosyltrehalose trehalohydrolase. This saccharide is available for various foods and has many useful functions; sweetening, low-damage to nutrients, and prevention of degeneration of starch and proteins. In this review, we present several functions of trehalose revealed by recent studies. Degradation of fatty acids and the formation of volatile aldehydes from fatty acids are remarkably suppressed by trehalose. This saccharide is preventive of the body odor (volatile aldehydes) of aged persons. In addition, trehalose has inhibitive effects on DNA-strand scission and protein modification by lipid oxidative products. Trehalose is effective in stabilizing vitamin C and SOD-like activity. Trehalose has shown ability to interact with minerals, including calcium chloride. Because of the interaction between trehalose and minerals, trehalose can be applied to improve of the property of mineral-containing products. From these results, it has been seen that trehalose has the benefits of lipid, minerals and vitamins other than starch and protein, including its function as a malti-functional saccharide. Trehalose has wide applications in foods, cosmetics and phamaceuticals.