Design Thinking in terms of startup is about finding if the problem worth to be solved by a new startup product or service. About 42% of startups fail because of “no market need”. Even if an idea seems a brilliant one, it is still necessary to make market research, customer observations, etc. It should be an on-going process from the very beginning of a startup existence, in order to be ready to pivot, to foresee problems and to reach success. There are many tools of Design Thinking, problem interview is one of them.