[Problem to be Solved]
To provide a secure system capable of satisfying the requirements of both users and providers of machine learning technology.
[Solution]
Provided is a conversion system in which a client device includes: an input-side conversion processing unit that is a part of the trained model extending from an input layer to a first middle layer of the trained model, and performs conversion processing based on the input data to generate a first intermediate output of the first middle layer of the trained model; a client-side transmitting unit that transmits the first intermediate output to a server; a client-side receiving unit that receives a second intermediate output from the server, the second intermediate output being generated in the server based on the first intermediate output and being a conversion output of the second middle layer closer to the output side than the first middle layer of the trained model; and an output-side conversion processing unit that is a part of the trained model extending from the second middle layer to an output layer of the trained model, and performs conversion processing based on the second intermediate output to generate the output data.