People with gait movement problems usually need the assistance of a knee orthosis device. A well-designed active or semiactive knee orthosis (SAKO) device can provide proper resistance torque to support an injured knee. Thus, gait phase or gait movement must be identified precisely for the control algorithm to determine the correct output torque command. In this research, we investigate the application of an inertial sensor for different locations on a shoe. Three inertial sensors are attached to the heel, side, and instep of one shoe for testing. Multiaxis acceleration signals from these three sensors are measured simultaneously for several gait cycles. The test results show that the shoe lateral sensor can provide proper signals of gait acceleration for the realtime gait control of the knee orthosis device.