A prediction system including a Central Processing Unit (CPU) and a memory storing a program. The CPU executes a control operation for controlling a control target, generates a prediction model based on a tree learning algorithm, acquires a predicted value by inputting, to the prediction model, a process value including one or more state values among state values that can be referenced by the CPU, acquires each of first and second execution times that are times taken for outputting the predicted value in response to input of first and second data to the prediction model, calculates a maximum execution time of the prediction model based on the first and second execution times, and evaluates the prediction model based on the maximum execution time.