The objective of this description is to provide a means for improving the solubility of a polysaccharide in water. Disclosed is a porous structure including a polysaccharide and having a multitude of pores wherein an average pore size of the pores is not smaller than 40 µm and a ratio of the number of pores having a pore size not smaller than 50 µm to the total number of the pores is not less than 30%.