Provided is a manufacturing method for monolithic structure that is a porous body formed of polysaccharide being a naturally-occurring polymer, has continuous pores with an average pore diameter suitable for biomolecule separation, and allows formation into arbitrary shape. The polysaccharide monolithic structure is manufactured by a method including a first step of obtaining a polysaccharide solution by dissolving polysaccharide into a mixed solvent of a first component and a second component at temperature lower than a boiling point of the mixed solvent, and a second step of obtaining polysaccharide monolithic structure by cooling the polysaccharide solution, wherein the first component is a solvent selected from lactate, and the second component is a solvent selected from water, lower alcohol, and a combination thereof. The monolithic structure obtained is a porous body having continuous pores with an average pore diameter of 0.01 to 20.0 micrometers, and a thickness of 100 micrometers or more.