Abstract: An impedance matching apparatus has: a storing portion 70 for previously storing, for plural positions which can be taken by a movable portion of a variable impedance element, allowable power values respectively corresponding to the plural positions of the movable portion; and an abnormality determining portion 80 for determining an allowable power value based on the present positions of the movable portion supplied from position detecting portions 41, 42 and the allowable power values stored in the storing portion 70, for comparing the allowable power value with an input power value, and for determining that it is abnormal when the input power value is larger than the allowable power value. Accordingly, the calculation load during the matching operation can be reduced.

Abstract: An impedance matching apparatus has: a storing portion 70 for previously storing, for plural positions which can be taken by a movable portion of a variable impedance element, allowable power values respectively corresponding to the plural positions of the movable portion; and an abnormality determining portion 80 for determining an allowable power value based on the present positions of the movable portion supplied from position detecting portions 41, 42 and the allowable power values stored in the storing portion 70, for comparing the allowable power value with an input power value, and for determining that it is abnormal when the input power value is larger than the allowable power value. Accordingly, the calculation load during the matching operation can be reduced.