To provide a humidifier capable of sterilizing properly in accordance with the generating amount of chlorine by an electrode. When a user pushes an operation switch, a CPU 11 makes the energization of the electrode 4 (S1) off. When a timer has counted the elapse of a time T1 (S2), the electrode is energized by a voltage supplying source 16 and a current supplying source 17 (S3), and the values of a voltage and a current between respective electrodes at that time are detected by a voltage detecting sensor and a current detecting sensor (S4). The CPU 11 determines the energizing time T1 and the non-energizing time T2 of the electrode 4 in accordance with the detected values based on the correlation table of the values of current, the generating amount of chlorine and the energizing time of the electrode 4 which are stored in an RAM12. |