Measurement instruments of physics, especially those dedicated as teaching aids in physics classroom are improving. These measuring instruments are not only used for measurement purposes, but also to apply theoretical concept into the real world, thus making it easier for students to comprehend. Therefore, this study aims to design, construct, and test a distance-measuring instrument based on the law of light reflection, especially for teaching physics. The method used in this study is quantitative-descriptive method, with the stages of designing, constructing, developing, and testing the distance-measuring instrument. The measuring instrument is constructed from simple, inexpensive, and easily obtained tools and materials, and it is an improvement version of a similar instrument previously developed. The testing stage of this instrument shows that the distance measurement results using the instrument is in good agreement with the results using a ruler depending upon the fixed flat mirror angle of the instrument.