Surface modification of ash powder was conducted to achieve better control of its mechanical properties in an ash-handling process, Flyash powder (JIS 10) was selected as a powder sample. and carbon black was selected as a fine particle. The powder was mechanically coated with fine particles. As a result, the fluidity of the powder was improved by adding a small amount of fine particles at room temperature. Addition of the fine particles also decreased the tensile strength of the flyash powder bed. and changed the displacement needed for the breakage of the powder bed.