NOVELTY - Method for producing powder containing crystalline alpha , alpha -trehalose dihydrate, involves subjecting liquefied starch to actions of starch debranching enzyme, cyclomaltodextrin glucanotransferase, alpha -glycosyl trehalose producing enzyme and trehalose releasing enzyme derived from Arthrobacter, and then to the action of glucoamylase to obtain alpha , alpha -trehalose-containing saccharide solution, crystallizing alpha , alpha -trehalose dihydrate, and extracting crystallized alpha , alpha -trehalose dihydrate by centrifugation, aging extract and drying the extract.    USE - The method is useful for producing powder containing crystalline alpha , alpha -trehalose dihydrate (claimed), which is used as raw material in foodstuffs, cosmetics and fuel, such as bioethanol.    ADVANTAGE - The method improves weight of starch to yield of product, produces product easily and with high purity, and has high crystallinity degree of 90-96% computed based on powder X-ray-diffraction profile, thus the powder is hard to solidify.    DETAILED DESCRIPTION - Method for producing powder containing crystalline alpha , alpha -trehalose dihydrate, involves subjecting liquefied starch to actions of starch debranching enzyme, cyclomaltodextrin glucanotransferase, alpha -glycosyl trehalose producing enzyme derived from microorganism belonging to Arthrobacter, and trehalose releasing enzyme derived from microorganism belonging to Arthrobacter and then to the action of glucoamylase to obtain alpha , alpha -trehalose-containing saccharide solution, crystallizing alpha , alpha -trehalose dihydrate from the saccharide solution, and extracting crystallized alpha , alpha -trehalose dihydrate by centrifugation, aging extract and drying the extract, where natural or recombinant enzyme derived from micro organism belonging to Paenibacillus or variant is used as cyclomaltodextrin glucanotransferase such that the content of alpha , alpha -trehalose in the saccharide solution is 86 %mass on an anhydrous basis, without subjecting to column chromatography fractionation step and having at least 98 %mass of alpha , alpha -trehalose on anhydrous basis.