A COMPOUND REPRESENTED BY THE FOLLOWING FORMULA (I), SALT THEREOF, OR HYDRATE THEREOF, CAN EFFECTIVELY RELIEVE ITCH CAUSED BY ATOPIC DISEASE OR THE LIKE: WHEREIN R REPRESENTS HYDROXYL,C₁₋₆ ALKOXY OPTIONALLY SUBSTITUTED WITH C₁₋₆ ALKOXY, OR AMINO OPTIONALLY SUBSTITUTED WITH C₁₋₆ ALKYL.