Disclosed are a composite oxide catalyst for preparing butadiene and a method of preparing the same. More particularly, a composite oxide catalyst, for preparing butadiene, including a metal composite oxide and AlPO4, and a method of preparing the same are disclosed.According to the present disclosure, a composite oxide catalyst for preparing butadiene, which includes a specific binder material, prevents generation of ingredients with a high boiling point, has superior catalyst strength, catalytic activity and butadiene yield, and a method of preparing the same are provided.