A toilet air cleaner includes an air-removal pipe line, a negative-pressure module and an air-cleaning water tank. The air-cleaning water tank communicates between the air-removal pipe line and the negative-pressure module for receiving water to isolate the air-removal pipe line from the negative-pressure module. Accordingly, foul and odorous gases in the toilet are drawn out, and are purified and deodorized by the air-cleaning water tank, so the risk of infection is reduced.