The present invention has objects to provide a method for inhibiting the formation of volatile aldehydes and/or the decomposition of fatty acids and use thereof. These objects are attained by establishing a method which comprises incorporating an α-oligoglucosyl α,α-trehalose(s) to a target product to inhibit the formation of volatile aldehydes per se and/or the decomposition of fatty acids per se in fatty acid-containing products; an inhibitory agent for inhibiting the formation of volatile aldehydes and/or the decomposition of fatty acids, which contains an α-oligoglucosyl α,α-trehalose(s) as an effective ingredient; and use thereof to thereby obtain various compositions such as food products, cosmetics, pharmaceuticals, and their materials and intermediates each having a high quality and stability.