Drain trap

Provided is a very durable wastewater trap that is easily maintained and that can prevent condensation. The wastewater trap comprises: a cylindrical main portion with a bottom in which a receiving pipe to receive a liquid and a discharging pipe to discharge the liquid are formed in a side wall; a removable dividing body that partitions the internal space of the main portion into a reservoir space and a discharge space; a cover that blocks the internal space of the main portion; and a sealing case that encloses at least a portion of the outer face of the main portion in which the reservoir space is formed so as to be in a sealed state. A gap is formed between the sealing case and the main portion. The sealing case and the main portion are transparent. The cover is configured to be removable when the sealing case is mounted on the main portion.