regulating containers 43 44 set to different pressures as in this embodiment three or more regulating containers may be used to set different pressures in this case three or more regulating containers are each equipped with an on off valve and in the case where the average value pca of the in container pressure pc is lower than the target value pc 0 the on off valve of only one of the three regulating containers of which the regulating container internal pressure is lower than and nearest to the target value pc 0 is opened while in the case where the average value pca of the in container pressure pc is lower than the target value pc 0 on the other hand the on off valve of only one of the three regulating containers of which the regulating container internal pressure is higher than and nearest to the target value pc 0 is opened according to this embodiment the electric heater 13 is used as a heating means for heating and vaporizing the working liquid 12 and therefore the heated portion temperature t 1 is calculated using equation 1 as in the second embodiment however the heated portion temperature t 1 may be calculated according to equations 1 2 using the heater 30 for exchanging heat.