We report here the case of a 67-year-old man who was initially diagnosed with myocardial hypertrophy with progressive hypertensive heart disease. After 6 years a cardiac biopsy was conducted because of changes in the electrocardiogram and transthoracic echocardiogram results, revealing amyloid deposition. Additional genetic studies revealed no TTR gene mutations, leading to a definitive diagnosis of wild-type transthyretin-related amyloidosis (ATTR). The patient started taking diflunisal as a stabilizer which is one of the advanced therapies for ATTR, and then the heart failure symptoms and brain natriuretic peptide (BNP) level improved in short-term follow-up. We present an elderly patient with ATTR, which is believed to be rare. We also discuss the apparent efficacy of novel therapeutic agents that increase the incentive to diagnose ATTR at an early stage. Therefore, we should always consider the existence of cardiac amyloidosis when we initiate the management of an elderly patient with cardiac wall thickening.