PROBLEM TO BE SOLVED: To provide a new aliphatic aldehyde having a methyl branch which has new aroma characteristics, and to provide a perfume composition, food and drinks, perfumes and cosmetics, a health and hygiene material and a medicine containing the new aliphatic aldehyde and 10-methylundecanal.SOLUTION: There are provided 5-methylundecanal and 6-methylundecanal, new aliphatic aldehydes having a methyl branch which are represented by the following chemical formula 1 and the following chemical formula 2. By adding at least one of these aliphatic aldehydes having a methyl branch and 10-methylundecanal to a perfume composition, a citrus feeling, a sweet feeling and a peel feeling are enhanced. Such a perfume composition is suitably used as an additive for foods and drinks, perfumes and cosmetics, a health and hygiene material and a medicine.
