Method for detecting cholangiocellular carcinoma and method of screening for prophylactic or therapeutic agent

Provided is a method for detecting cholangiocellular carcinoma, the method involving measuring the level of periostin gene expression, the expression of periostin proteins, or the amount of periostin proteins, in a biological sample taken from a test subject. Also provided is a method of screening for cholangiocellular carcinoma, the method involving measuring the level of periostin gene expression or the amount of periostin proteins in a culture where cells that can produce periostin have been cultured in the presence of a candidate substance. Thus, it is possible to provide a method for detecting cholangiocellular carcinoma using a marker and a method of screening for a prophylactic or therapeutic agent for cholangiocellular carcinoma.