The present inventors discovered that neural invasion is suppressed by inhibiting IL-6 in a model for neural invasion of pancreatic cancer, and completed the present invention. The present inventors also demonstrated that: an IL-6 receptor is expressed in cells of human pancreatic cancer cell lines; and IL-6 enhances the chemotactic and migratory activities and intracellular signaling of pancreatic cancer cells; and thus pancreatic cancer can be treated by inhibiting IL-6. Furthermore, the present inventors found that neural invasion of human pancreatic cancer can be suppressed, from the results of administering IL-6 inhibitors to neural invasion model mice.