A method of controlling a variable valve timing system comprising calculating, by a sliding mode control, a first control amount based on a deviation between a target value and an actually measured value of the position of the displacing member of the variable valve timing system, calculating a second control amount by integrating the deviation as an input when the deviation falls within a predetermined numeric value range containing a zero value, or by integrating the zero value as the input when the deviation falls outside the predetermined numeric value range; and adding the first control amount and the second control amount to set a compensation control amount for compensating the position of the displacing member.