 Nalfurafine hydrochloride is a selective kappa-opioid receptor agonist developed in Japan, and in May 2015 the use of nalfurafine hydrochloride was officially approved in Japan for pruritus in patients with chronic liver diseases including PBC. In the current study, the investigators aimed to assess pruritus and overall QOL before and after administration of nalfurafine hydrochloride in patients with PBC. Furthermore, the investigators took serum sample from the enrolled patients and examine the association of pruritus with possible biomarkers. 