A control system for controlling an operation of a production device, the control system comprising a learning device and a control device, the learning device comprising: a learning data acquiring unit configured to acquire a plurality of learning data sets, wherein each learning data set includes a combination of first data associated with a factor determining an operation of the production device and second data associated with a command value for the production device which is adapted to the factor indicated by the first data; a learning processing unit configured to construct a prediction model by performing machine learning using the acquired plurality of learning data sets, wherein the prediction model outputs, for each of the acquired plurality of learning data sets, a value corresponding to the second data when the first data is input; an estimation unit configured to estimate a numerical value range of the command value from a distribution of command values associated with the second data in the acquired plurality of learning data sets, wherein the distribution of the command values is approximated by one of a normal distribution, a gamma distribution and an exponential distribution; and a threshold value determining unit configured to determine a second threshold value for the command value for the production device on the basis of the estimated numerical value range such that a first acceptable range which is defined by a first threshold value preset for the command value for the production device is extended; the control device comprising an input data acquiring unit configured to acquire input data associated with the factor in an operational phase; a prediction operation unit configured to acquire an output value from the prediction model by inputting the acquired input data to the prediction model and to determine the command value for the production device on the basis of the acquired output value, wherein the determined command value is within a second acceptable range which is defined by the determined second threshold value; and an operation control unit configured to control the operation of the production device on the basis of the determined command value. a learning data acquiring unit configured to acquire a plurality of learning data sets, wherein each learning data set includes a combination of first data associated with a factor determining an operation of the production device and second data associated with a command value for the production device which is adapted to the factor indicated by the first data; a learning processing unit configured to construct a prediction model by performing machine learning using the acquired plurality of learning data sets, wherein the prediction model outputs, for each of the acquired plurality of learning data sets, a value corresponding to the second data when the first data is input; an estimation unit configured to estimate a numerical value range of the command value from a distribution of command values associated with the second data in the acquired plurality of learning data sets, wherein the distribution of the command values is approximated by one of a normal distribution, a gamma distribution and an exponential distribution; and a threshold value determining unit configured to determine a second threshold value for the command value for the production device on the basis of the estimated numerical value range such that a first acceptable range which is defined by a first threshold value preset for the command value for the production device is extended; the control device comprising an input data acquiring unit configured to acquire input data associated with the factor in an operational phase; a prediction operation unit configured to acquire an output value from the prediction model by inputting the acquired input data to the prediction model and to determine the command value for the production device on the basis of the acquired output value, wherein the determined command value is within a second acceptable range which is defined by the determined second threshold value; and an operation control unit configured to control the operation of the production device on the basis of the determined command value.