Tampering monitoring system can detect whether protection control module is tampered with even if some of detection modules are tampered with. Tampering monitoring system includes protection control module detection modules, and management device. Protection control module includes: generation unit generating d pieces of distribution data from computer program, n and d being positive integers, d smaller than n; selection unit selecting d detection modules; and distribution unit distributing d pieces of distribution data to d detection modules. Each detection module judges whether received piece of distribution data is authentic to detect whether protection control module is tampered with, and transmits judgment result indicating whether protection control module is tampered with. Management device receives judgment results from d detection modules and manages protection control module with regard to tampering by using received judgment results.