The purposes of the present invention are to provide a depot preparation which can form depots easily and can maintain the depot-formed state for a long period if desired and to provide a depot preparation which, when the depot preparation contains a drug, can release the drug sustainably over a long period after in vivo administration thereof. The present invention relates to a depot preparation containing a trialkyl citrate and/or an acetyltrialkyl citrate, wherein an alkyl group contained in the trialkyl citrate and an alkyl group contained in the acetyltrialkyl citrate are the same as or different from each other and each of the alkyl groups has 3 to 5 carbon atoms.
