A simulation-based approach provides a hint to study a solution to various problems. To show the feasibility of this approach in our research, this paper focuses on the congestion problems which can be found in various fields, including service counters at peak times, cafeteria at lunch times, road traffics in rush hours, and logistics control in a tight schedule. Ticket counter simulation was studied and implemented as a web-based simulation program. Human crowds control simulation and traffic simulation model were implemented with a general simulator, and evaluation on these models were studied to propose a solution to the congestion problems. Logistics control simulation was studied using an agent-based framework. Reviewing all of these application examples, this paper shows how the simulation-based approaches work towards congestion problems.