The Associated Press report said DoCoMos's group net income came in at 457.3 billion yen ($3.81 billion) for the fiscal year ended March 31, down from 610.5 billion a year earlier.
Revenue rose 0.5% to 4.788 trillion yen ($39.90 billion), up from 4.765 trillion yen a year ago, the report said.
The report said the profit decline was caused by increased sales promotion fees paid to the company's sales agents amid intensifying competition in the country's cellphone market, according to NTT DoCoMo spokesman Shinjiro Minami.
Also squeezing the income was a lack of special gains booked in fiscal 2005, when NTT DoCoMo gained vast proceeds from the sale of shares in Hutchison 3G UK Holdings and KPN Mobile, Minami, quoted by the Associated Press report, said.
The company did not break down quarterly earnings, the report further said.