The objective of research is to evaluate whether the system of raw material purchase and cash expense at PT. Malang Indah Genteng Rajawali Malang is reliable or not. The purchase of raw material is one of important activities conducted by manufacture companies. Purchase activity is always followed by cash expense activity. Therefore, accounting system of raw material purchase and cash expense will need good internal control. Research type is descriptive with case study approach. It attempts to measure how far the effectiveness of accounting system of raw material purchase and cash expense can support internal control. Result of research indicates that raw material purchase system and cash expense to support internal control in the company has been challenged with limitations. Accounting system applied in the company is too simple such that there is still functional trap, and insufficient number of accounting blank and note as the recording device of the activity in the company. Some of these weaknesses are less supportive to the internal control such that the company needs to improve the system. One way to improve is that by separating the function that cannot be overlapped and completing the accounting blank and note used by the company.