With the development of the financial market, early retirement is possible. In this paper, I investigate an optimal voluntary retirement policy of an ecomomic agent who is a wage earner with a fixed mandatory retirement time. The retirement policy is chosen considering the trade-off between labor income and utility loss from labor. I transform the original problem to a pure optimal stopping problem by applying the martingale and duality argument, and use the binomail method to obtain the numericlal solutions for the optimal retirement policy. I also provide some comparative statics with the numerical solutions
