The purpose of this study is to prevent further misunderstanding regarding hijab for Moslems in Surabaya, understanding the correct knowledge of hijab will affect hijab manufacturers to produce hijab in accordance with Islamic Shari’a. This research is causal conclusive type with quantitative approach, since it aims to test specific relations. Analytical technique used in this research is logistic regression analysis to reveal the strength of prediction on knowledge level towards hijab purchasing decision. The results that the level of customer knowledge in hijab purchase is still at the level of know-how, which is not yet at the know-why level. Customer’s buying decision of hijab is based on the quality and color of the fabric, then whether the brand is famous or not. Afterwards, customer generally gains more knowledge regarding hijab and prefer hijab that is complying Islamic Shari'a.