A technique for compressing and transmitting data without hampering real-time performance can be offered. In a data compression transmission system for collecting data generated by a plurality of devices at a central server via a network, an intermediate server is arranged between the devices and the central server. Each of the devices includes a packet cache processing unit for converting the generated data to a hash value based on a cache. The intermediate server includes a packet cache processing unit for decoding the hash value to original data based on the cache, a buffering unit for aggregating the data and outputting the data as a long packet, and a compression encoding unit for compressing the data and generating encoded data.