The subject is providing a crystallizing device of a biopolymer, which made to form biopolymer crystal efficiently in crystallization solution of a small amount of biopolymers by applying a low voltage and not to make an electrode disturb but observable a state of crystal formation. As an electrode for applying an electric field to a biopolymer solution, a transparent conductor, which does not disturb crystal formation, is used. Between the transparent conductor electrodes 2s, the electric insulating member 4 is placed and the crystallization solution 1 for a small amount of biopolymers is maintained inter-electrode. A biopolymer is efficiently crystallized by applying a low voltage supplied from the voltage generator 5 to the transparent conductor electrode 2. A crystal formation state of a biopolymer is optically observable from the electrode side of a transparent conductor. Orientation control of the biopolymer can be performed by an electric field formed by the above-mentioned voltage application.