<p>A simple and inexpensive fixing structure for fixing an antibacterial agent exhibiting a significant bacteriostasis effect. In the vicinity of the suction port (23) of a drain pump (16) of an air conditioner within a drain pan (8), an antibacterial agent unit (K) comprising an antibacterial agent (19, 19, ...) capable of being brought into contact with drain water (D) is arranged, so that the antibacterial agent unit (K) arranged in the vicinity of the suction port (23) of the drain pump (16) at the lowest portion in the drain pan (8) is immersed completely into the drain water (D) when the drain pump (16) is operating and not operation.</p>