This master thesis deals with the topic of risk management and explains its importance during project management in IT projects. It descibes every phase of the risk management life cycle and also methods and procedures used in each phase. After that the thesis focuses on decision analysis, mainly on decision trees and Monte Carlo simulation. The last part contains the design of an application for risk management and visualization. Prototype of this system has been implemented based on this design in PHP framework Laravel. Details of the implementation and testing are in the next part of this thesis. In the end there is an assessment with discussion of possible expansions.