The present invention provides a .beta.-chitin complex composed of an inclusion compound formed by using a .beta.-chitin as a host and a guest compound which is a compound having a functional group that can form a hydrogen bond with a hydroxyl group and/or an amide group of the .beta.-chitin and having a melting point of at least 60.degree. C. The .beta.-chitin complex is prepared by a method comprising the step of heating a guest compound to its melting point or higher to prepare a melt of the guest compound and the step of immersing an anhydrous .beta.-chitin in this melt, or a method comprising the step of dissolving or suspending a guest compound in a solvent to prepare a guest carrier solution and the step of immersing a .beta.-chitin in the guest carrier solution.