Mycoplasma pneumoniae is the most common bacterial strain causing atypical pneumonia in children and adolencents. Although it is known to cause mild symptoms, it can also cause severe pulmonary or extrapulmonary complications in rare cases. Necrotizing pneumonia (NP) is often reported as a complication of Streptococcus pneumoniae and is very rarely caused by M. pneumoniae. We report a case in which a 5-year-old boy was diagnosed with lobar pneumonia with symptoms that aggravated even with macrolide antibiotic treatment. Anti-mycoplasma pneumoniae Ig-M test yielded high values, and direct polymerase chain reaction results were also positive. NP caused by M. pneumoniae was confirmed on computed tomography. After treatment involving tosufloxacin and systemic steroid, the lesion decreased in size and improved gradually when followed-up for more than 1 year. The patient did not have any predisposing or risk factors for NP.