The present invention provides an antibody against a periostin isoform having anti-cell adhesive activity, especially an anti-periostin antibody having the ability to neutralize anti-cell adhesive properties, as well as a prophylactic or therapeutic agent for periostin-related diseases comprising the antibody. The present invention also provides methods for detecting and quantifying the periostin isoform in a sample by using the antibody, as well as a method for diagnosing periostin-related diseases comprising measuring the amount of the periostin isoform by the detection or quantification method.
