Body movements monitoring may allow preventing, diagnosing, and recovering several wrong attitudes that could lead to possible future diseases. A multisensor system was developed to measure thigh movements in free-living environments all-day long especially during walking. The device is a very simple and portable system based on low-cost technology. It is composed of an inertial sensor and a strain sensor for detecting thigh movements, and of a microcontroller and a Bluetooth module. The measurement data are collected and sent wirelessly to a PC for storing and further analyses. We validated and tested the wearable system on ten healthy subjects during walking and running by using an accurate inertial motion capture (Mo-cap) system. The inclination of the thigh measured by the proposed system has differed of maximum 5.5° with respect to the flexion/extension measured by the Mo-cap system. Furthermore, the experimental results have showed that the strain sensor output can also be related to the muscle activity during walking. This assumption has further been sustained when the system is tested during running. Thanks to its high wearability, wireless communication over long distances, and long-battery life, the system could be adopted for domestic applications.