As reported by Bloomberg Businessweek, Tokyo's MM Research Institute Ltd. issued a report that said Apple sold 1.69 million units in the 12-month period ending March 31. That took the lion's share of the total 2.3 million handsets sold in Japan in the same frame.
Apple's sales in Japan have doubled, while competitors have lost ground. The second-largest smartphone manufacturer was HTC, which took just 11 percent of the market. Toshiba was third with 6.8 percent.
The total is a significant increase from a study released in December 2009, which declared that the iPhone represented 46 percent of all Japanese smartphone sales. That research from Impress R&D found the iPhone 3G took 24.6 percent of the consumer market, while the iPhone 3GS accounted for another 21.5 percent.
Apple's astounding success in Japan has been partially credited to aggressive marketing from exclusive carrier SoftBank Mobile, which has offered competitive pricing and pushed the handset with high profile advertising.
MM Research expects smartphone sales in Japan to exceed 3 million in the next year. The firm expects the next 12 months to be "much more competitive."
Apple's smartphone rival Google has captured about 5.6 percent of the market with its Android smartphones, according to MM Research. That's expected to grow in the next year, with Softbank expanding its Android lineup, along with rivals NTT DoCoMo and KDDI Corp.
Japan is a strong market for Apple. Just this week, in its quarterly earnings report, Apple revealed that it earned $887 million there from Mac sales in the first quarter of 2010, a 51 percent increase from a year ago, with 18 percent growth in Mac shipments. During the company's conference call on Tuesday, Chief Operating Officer Tim Cook revealed that iPhone units in Japan grew 183 percent year-over-year in the last quarter. The Asia Pacific market as a whole saw 474 percent growth over a year prior.
"These are some fabulous numbers we are seeing just incredible demand for iPhones," Cook said.
Bloomberg Businessweek calculated that Japan was responsible for 6.6 percent of the company's revenue last quarter, which was its highest total since 2006.