This IDC study is a translation of the Japanese document IDC #JPJ42862717. It presents IT spending performance in 2015 and 2016, as well as IT spending forecast from 2017 to 2021 in the Japan IT market by company size and industry segment. For market analysis and forecasting purposes, IDC classifies the industry segments into 17 business segments and four nonbusiness segments and the company sizes into five sizes. Starting from this study, IDC made changes to the Japan IT market product classifications following the changes in the product classifications in the IDC Worldwide Black Book. These changes include the separation of the hardware market into the device market and the infrastructure market, the addition of infrastructure as a service (IaaS) segment to the infrastructure market, and the addition of the business services market. IDC forecasts strong growth in the Japan IT market until 2019. However, this growth will be driven by the newly added business services market and IaaS, in addition to PC and other markets, while growth in the server, external enterprise storage systems, and IT services markets is expected to remain relatively low. "As changes in user companies' spending trends are manifesting themselves in the Japan IT market, IT suppliers must propose solutions that exceed the IT framework and meet user companies' needs," says Hitoshi Ichimura, group research manager, IT Spending, IDC Japan.