Disclosed is a method for monitoring activity of a subject and a monitoring device therefor. The method comprises, detecting the direction of the monitoring device with respect to a hand of a subject by measuring a signal of y-axis for a time ty and averaging the signal measured. The method further comprises, detecting the hand on which the subject carries the monitoring device by measuring a signal of the x-axis for a time tx and averaging the signal measured. The method also comprises, using the obtained information to optimise the activity monitoring, and further to determine a main axis of motion of the monitoring device and direction of the main axis of motion in order to improve recognition of the activity of the subject.
