An air purification device includes an electrode unit, an electrifying part, a polarity switching part, a current detection part, a determination part and a reporting part. The electrode unit electrolyzes water. The electrifying part performs an intermittent electrification by alternately switching the electrifying time in which the electrode unit is electrified and the non-electrifying time in which the electrode unit is not electrified. The polarity switching part reverses the polarity of the electrode unit. At the beginning of an initial electrifying time after reversing the polarity of the electrode unit, the current detection part detects the peak current flowing on the electrode unit. The determination part determines the salinity concentration of water according to the value of the detected peak current. The reporting part makes a report according to the determination result of the determination part.一種空氣清淨裝置,其具備電極單元、通電部、極性切換部、電流檢測部、判定部、與報知部。電極單元會將水電解。通電部會將對電極單元進行通電之通電時間與對電極單元不進行通電之非通電時間交互地切換來進行間歇通電。極性切換部會反轉電極單元的極性。電流檢測部是在反轉電極單元的極性後的最初通電時間之開始時,檢測在電極單元流動的尖峰電流。判定部是根據被檢測出的尖峰電流的值來判定水的鹽分濃度。報知部是根據判定部的判定結果進行報知。