Asthma exacerbation is associated with respiratory infections, including those by viruses and atypical bacteria. We herein report a case of severe acute asthma in an adult caused by Chlamydophila pneumoniae (C. pneumoniae) infection. A 39‐year‐old woman without a history of asthma reported to the emergency department with progressive worsening of cough, shortness of breath, and wheezing with low oxygen saturation. A computed tomography (CT) scan revealed patchy ground‐glass opacity and bronchial wall thickening. She was treated with systemic corticosteroids, inhaled short‐acting β2 agonists, aminophylline, doripenem, and levofloxacin. Through successful treatment in the intensive care unit (ICU), her condition and the chest X‐ray and CT findings improved. Chlamydophila pneumoniae infection was confirmed by elevated paired serum C. pneumoniae‐specific IgA antibodies. Chlamydophila pneumoniae infection is an important cause of severe acute asthma. On CT, findings typical of C. pneumoniae pneumonia were noted.