Active oxygen volume measurement device, active oxygen surface processing device, active oxygen volume measurement method, and active oxygen surface processing method

An objective of the present invention is to accurately measure an active oxygen surface effect volume in a surface process using active oxygen. This active oxygen volume measurement device comprises: a first sensor further comprising a first oscillator which is positioned near an object to be processed, and which outputs a mass change in the first oscillator based on the active oxygen effect volume as a first frequency change quantity; a second sensor further comprising a second oscillator which is positioned near the object to be processed, and which outputs a mass change in the second oscillator based on a disturbance caused by a change in temperature, humidity, or pressure, as a second frequency change quantity; and a measurement unit which is configured to compute the difference between first frequency change quantity and the second frequency change quantity, and to identify the difference as a frequency change quantity by the actual active oxygen effect volume.