A CT value controller includes a storage means, an input means, and a computing means. The storage means stores a function expressing a relative humidity and a CT value regarding a degradation degree of an anticancer agent, an assumed relative humidity, and a CT setting. The input means inputs a measured relative humidity and a measured ozone concentration at a time of degradation treatment of the anticancer agent. The computing means calculates a corrected CT value increment based on a difference between the measured relative humidity and the assumed relative humidity at every input of the relative humidity and the ozone concentration by using the function. The computing means determines a termination of the degradation treatment of the anticancer agent when an integrated CT value of the corrected CT value increments reaches the CT setting.