Immune checkpoint inhibitor (ICI)-induced immune-related adverse events (irAEs) should be managed differently from conventional chemotherapy. Particularly, hepatic dysfunction poses various problems, including affecting the timing of steroid or immunosuppressive agent initiation and affecting the treatment of refractory cases. Therefore, we investigated the clinical characteristics of irAEs, especially ICI-induced immune-mediated hepatotoxicity (IMH), in 370 patients who received ICI at our hospital. Although the overall frequency of irAEs was 41.1%, the frequency of IMH was 5.1%. Furthermore, most patients recovered after treatment according to the guidelines; however, some fatalities and refractory cases were recorded and cytomegalovirus infection was a problem during the treatment process. Hence, we report two refractory cases and discuss the treatment strategy adopted at our hospital.