Bordetella parapertussis is one of the bacteria that causes whooping cough. However, little attention has been paid to this bacterium because it causes a milder illness than Bordetella pertussis and the rate of detection is low, even though research suggests that pertussis vaccines have limited efficacy against B. parapertussis infection. However, recent studies have revealed high rates of detection in patients with whooping cough in some field studies. In this review, the relevant studies of B. parapertussis are summarized and it is demonstrated that it is now necessary to pay greater attention to infections by this bacterium.