As pneumatic-related industry has advanced and the confidentiality of pneumatic components is required, the demand for solenoid valves with ultrahigh ON/OFF time performance is rapidly spreading in aerospace-related industries. Special-purpose pneumatic control solenoid valves, which have been researched and developed by the state and whose operational suitability and reliability have been verified, are spreading to civil industry as well. To improve the performance of solenoid valves for pneumatic control, the quality of the major parts was improved, and various experiments were performed on the main parts inside the valve body, such as springs, seat bodies, and pistons. Through the quality improvement of these major parts, the effects of the performance improvement in terms of ON/OFF time, flow rate, and leakage of solenoid valves were verified.