Tracking object poses in 3D is an important technology in augmented reality applications. We propose an instant motion tracking system that tracks the object's pose (3D bounding box) in real-time on mobile devices. Our system does not require any prior sensory calibration or initialization sequence to perform. Objects are detected and their initial 3D pose is estimated using a deep neural network. Then the estimated pose is tracked using a robust planar tracker. Our tracker is capable of performing relative-scale 6-DoF tracking in real-time on mobile devices. By combining CPU and GPU usage efficiently, we get 25-FPS+ performance on mobile devices.