We treated a patient with keratitis caused by Mycobacterium chelonei (M. chelonei). The patient was a 74-year-old man who had been successfully treated for stromal type herpetic keratitis with topical steroids. The corneal lesions appeared chalky white with indistinct margins and had radial projections in deep level stroma. M. chelonei was found in second corneal scrapings. Topical tobramycin that had sensitivity resolved the keratitis rapidly. M. chelonei keratitis has been reported in only 25 cases so far and this case is the first report in Japan. M. chelonei keratitis occurred mostly in eyes which had been subjected to trauma, surgery, and the use of topical steroids. If these characteristic corneal findings appear in such predisposed eyes, M. chelonei keratitis should be considered.