The aim of this study is to examine learning by middle management through the experience of new business incubation. We carried out a study consisting of semi-structured interviews of 15 middle managers working in new business departments of private enterprises. We analyzed the qualitative data from the 15 participants on the basis of the Modified Grounded Theory Approach(M-GTA) and constructed a learning process model. As a result of the M-GTA based analysis, it became clear that the learning of middle management through the experience of new business incubation had four phases: I. the responsibility avoidance phase, II. the reality acceptance phase, III. the critical reflection phase, and IV. the perspective transformation phase.