1. A control system for a plant, comprising: identifying means for identifying a model parameter vector of a controlled object model obtained by modeling said plant; and a controller for controlling said plant using the model parameter vector identified by said identifying means; said identifying means including: identifying error calculating means for calculating an identifying error of the model parameter vector; limiting means for liming the identifying error in a predetermined range; and updating vector calculating means for calculating an updating vector according to the identifying error limited by said limiting means, wherein said identifying means calculates the model parameter vector by adding the updating vector to a reference vector of the model parameter vector.