An event gathering method includes: storing cost information between nodes which manages by associating a transmission node identifier and a reception node identifier with a first communication cos, the communication occurring between nodes including a sensor node which transmits an event and an intermediate node which relays the event; modifying or storing the event; gathering cost information between modules which manages by associating a transmission module identifier and a reception module identifier with a second communication cost of a occurred event; extracting a pattern candidate which assigns modules to first nodes as deployment pattern candidates which manages by associating a module identifier with a node identifier; computing a total communication cost based on the cost information between modules and the cost information between nodes; selecting a deployment pattern candidate having the smallest total communication cost; and deploying the modules in the first nodes based on a selected deployment pattern candidate.