The established supply chain format has been radically changing from a three-month production to a shortened lead-time in the fashion industry. The faster pace of fashion trends, changing consumer lifestyle, and consequent demands for newness have been mainly attributed to the rapid development of high-tech information systems and mass communication. In particular, global fast-fashion leaders have become more successful by producing not as was initially planned and forecasted, but with an agility subject to customer responses. Latest customer trends are captured quickly, and production and distribution is steered to meet the response. In order to further maximize benefits and efficiency in a sustainable manner, the fast-fashion industry is seeking a production optimization model under which product attributes are defined in a short period of time, and an optimal quantity of products by style is produced. This paper aims to provide an optimal production quantity which subsequently requires an optimal parts procurement from the perspective of the supplier. This is obtained in order to minimize the cost function by identifying cost factors through an economic analysis technique. In this study, we propose a model for optimal production and its parts procurement to maximize target sales and profits by taking inventory and pricing into account.