To directly detect an abnormal temperature of process gas.SOLUTION: A characteristic measurement section 3 acquires a change characteristic of a pressure during vacuum drawing when a temperature of a medium to be measured is normal (a change characteristic of a normal pressure) and stores the acquired change characteristic of the normal pressure in a reference characteristic storage section 4 as a reference pressure change characteristic I. During a process or at the timing of vacuum drawing performed before and after the process, the characteristic measurement section 3 acquires a change characteristic II of a pressure of an object to be compared. A state determination section 5 compares the change characteristic II of the pressure from the characteristic measurement section 3 to the reference pressure change characteristic I stored in the reference characteristic storage section 4 to determine whether or not some abnormality occurs in the temperature of the medium to be measured.SELECTED DRAWING: Figure 6
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