This study compared the work environment colors and the colors of working clothes by conducting a field survey of domestic machinery manufacturers who are playing a central role in Korean industries so as to develop and evaluate working clothes based on the safety of workers and environmental harmony. For the study method, after the color-related requirements were collected through interviews and field surveys, the fabrics for working clothes were woven and the colors were selected using the requirements. The designs of working clothes were developed with an emphasis on color design. The colors of the working clothes were also analyzed in their relationship to the working environment. The evaluations were separately performed for the appearance and the colors with workers of D machinery manufacturing company. The appearance and color satisfaction, safety, psychology, and harmony with environment were evaluated on a 5-point scale by workers and their safety managers. Furthermore, pictures of the workers in their existing working clothes and the newly developed working clothes were taken with a digital camera while they were working in the field. The RGB values of the pictures were extracted using Photoshop ver. 7.01, which were converted to HVC values using Munsell Conversion ver. 4.0.1. This study found that higher satisfaction levels were shown for the newly developed working clothes compared to the existing ones. The actual measurements also showed that the newly developed had higher brightness and clearer chromatic contrast than the existing ones, indicating higher explicitness and attention for safety of workers. These types of studies can contribute to the integrated working environment plan of machinery manufacturers.