To provide a new method capable of producing a biopolymer crystal simply and efficiently.

This method for producing the biopolymer crystal is characterized by comprising a vibration process for vibrating a container housing a mixed liquid obtained by mixing a crystallization agent solution with a biopolymer solution, and a storing process for storing the container housing the vibrated mixed liquid, and the method for producing the biopolymer crystal is characterized by comprising the vibration process for vibrating the container housing the biopolymer solution, the vibration process for vibrating the vibrated biopolymer solution and the container housing the biopolymer solution, the mixing process for mixing the vibrated biopolymer solution with the crystallization agent solution, and the storing process for storing the container housing the mixed liquid.