The present invention provides a process for producing silylated pullulan, which features reacting pullulan with N,O-bistrimethylsilylacetamide by using, as a reaction medium, only one of N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone or a mixed solvent of both of them. Compared with conventional processes, the process according to the present invention can produce high-purity silylated pullulan simply, easily and efficiency.