The master´s thesis deals with the design of the position locking mechanism of the backrest of the car seat in the folded Easy-Entry position. The thesis contains analyzing the current state of the mechanism and evaluating the force needed to release the backrest from the folded position. Furthermore, the thesis contains a procedure of designing a new solution, evaluating the force needed to release the backrest from the folded position, and comparing it to the old design. The thesis also includes mechanism simulation and technical documentation and calculation tables are situated in the annexes.