A method for controlling a simulation system includes storing first-stage and second stage tables in which a value of a predicted time until arrival of an I/O instruction and a type of the instruction are included as entries for each program counter of an instruction set simulator, and in which a value of an earliest time until an output event from a peripheral simulator is included as an entry for each type of instruction; looking up the first-stage table to obtain the type of the instruction and the value of the predicted time until arrival of the instruction, looking up the second-stage table with reference to the obtained type of the instruction to obtain the value of the earliest time until the output event from the peripheral simulator, and returning the predicted time until arrival of the instruction and the earliest time until the output event from the peripheral simulator.