The process of implementing construction projects often encounters changes. One of these changes is the change order. After recognizing its existence, the change is formalized by the issuance of a change order, which is a document that describes the scope of the change and its impact on project performance. If agreement is not reached between project participants on the changes, it becomes a claim or dispute that can negatively affect project implementation and reduce the chances of project success. Changes in construction projects are frequent and can occur from many different sources, for many different reasons, at any phase of the project and can have far-reaching impacts. This study aims to identify the factors that cause Contractual Change Order (CCO) to arise during the construction phase of building projects in Banda Aceh. This study uses a quantitative method with data collection techniques through distributing questionnaires to 36 contractor companies in Banda Aceh City. Data testing was done with validity and reliability tests, while the data analysis used was descriptive. From the research results, 16 CCO factors were identified during the construction project implementation phase. It was determined the two main causes of change orders from the contractors` view are bad weather conditions and soil conditions.