The cryptocurrency marketplace provides liquidity receiving orders from investors. This requires managing the appropriate inventory risk. An optimal liquidation strategy based on stochastic control has been proposed for such inventory risk management problems of FX dealers. However, the cryptocurrency market has different characteristics than the FX market. Therefore, we propose an optimal liquidation strategy based on stochastic control that considers the characteristics of the cryptocurrency marketplace. We also perform an empirical study using the trading data of a cryptocurrency marketplace. We show that order bias affects the optimal liquidation strategy, and our proposed method is more effective than simple liquidation strategies.