A water purification device includes: at least one base material carrying denitrifying bacteria； a holding portion holding the base material； a sprinkler mechanism for spraying water to be treated onto the base material； and a drainage mechanism provided at The holding portion is configured to discharge the water to be treated such that at least a portion of the substrate is always exposed from the water to be treated.一種水淨化裝置，包括：至少一個基材，擔載有脫氮細菌；保持部，保持所述基材；灑水機構，將被處理水灑至所述基材上；以及排水機構，設置於所述保持部，且以使所述基材的至少一部分始終自所述被處理水露出的方式排出所述被處理水。
