The purpose of this study is to develop a Skier Training System for monitoring skiing courses and analyzing skier posture using smartphones. The system is composed of three elements: first, operating servers that receive information on the skier’s exercise; second, Skier Training Apps developed using Java and C based on Android SDK 4.2 or above; and third, Data Gathering Gear embedded with gyroscope sensors and GPS for measuring skier stance. When a skier wearing our Data Gathering Gear runs down a slope, his or her stance is uploaded to the operating servers. Then the servers calculate the recorded data, such as velocity and turn trajectory, in order to suggest body angles that are optimized for the skier; subsequently, the skier can improve his or her skills by checking his or her records, and then attempt to correct his or stances based on the suggestions offered by the Skier Training Apps.