In a sensor relay apparatus (10), a storage unit (11) stores a communication protocol correspondence list (22B) in which a sensor terminal (ST) and a communication protocol are registered in association with each other, and a communication format (22C) to be used in the communication protocol, a relay processing unit (12) communicates with the sensor terminal (ST) specified in the communication protocol correspondence list (22B) based on the communication protocol associated with the sensor terminal (ST), receives sensor data detected by the sensor terminal (ST), converts the format of the sensor data based on the communication format (22C) in association with the communication protocol, and relays and transfers the sensor data to a processing apparatus (20), and a relay managing unit (16) updates the communication protocol correspondence list (22B) or the communication format (22C) in the storage unit (11), based on a communication protocol correspondence list or a communication format newly notified from the processing apparatus (20).