Provided are a behavior-disrupting agent of Argentine ants for controlling them or suppressing their reproduction is a safer and more effective manner, and the behavior-disrupting method of them. More specifically, a behavior-disrupting agent of Argentine ants comprising Z-9-hexadecenal, and a behavior-disrupting method of Argentine ants comprising a step of using the behavior-disrupting agent are provided based on the finding that the behavior of Argentine ants is disrupted by emission of Z-9-hexadecenal, which is a trail pheromone, into the atmosphere.