A wearable device (10) to assist with the movement of limbs (50, 51) connected at a joint (52), the device (50) comprising: a linear motion generating unit (20) to generate linear motion, the unit (20) having distal end portions operatively connected to the limbs (50, 51), whereby the linear motion generated by the unit (20) causes the limbs (50, 51) to move and pivot about the joint (52); a force measuring unit (30) to measure a change of force applied to the limbs or linear motion generating unit (20); and a displacement measuring unit (40) to measure the displacement of the linear motion generating unit (20) when linear motion is generated; wherein a predetermined distance of linear motion having a predetermined velocity is generated by the linear motion generating unit (20) to assist with the movement of the limbs (50, 51) based on the change of force measured by the force measuring unit (30) or the displacement measured by the displacement measuring unit (40).