Diabetic foot infection is one of the important complications in patients with advanced diabetes mellitus. Limb threatening infections such as osteomyelitis, abscess, and necrotizing fasciitis are frequently accompanied by the disease. Non-tuberculous mycobacterium (NTM) is a rare causative organism of diabetic foot infection. Thus, if one is not suspicious or meticulous, infection due to NTM will be easily overlooked and this will result in delayed diagnose and treat. Therefore, it is necessary to consider NTM as the causative organism if the wound does not respond to the conventional antibiotic treatment and the culture from the adequately obtained specimen reveals atypical acid-fast bacilli. We present a case of diabetic foot infection with osteomyelitis and abscess due to Mycobacterium mageritense, one of the rapid growing mycobacteria, that was successfully treated with surgical debridement and appropriate antibiotic treatment.