There is provided an activity recognition apparatus for detecting an activity of a subject. The apparatus includes: a sensor unit (10) including a plurality of linear motion sensors configured to detect linear motions and a plurality of rotational motion sensors, the linear motions being orthogonal to each other, the rotational motions being orthogonal to each other and a computational unit (20) configured to receive and process signals from the sensors included in the sensor unit so as to detect an activity of the subject. The sensor unit (10) is directly or indirectly supported by the subject with an arbitrary orientation with respect to the subject. The computational unit (20) performs a calculation that uses the signals from both linear motion sensors and rotational motion sensors to determine the activity of the subject independent of the orientation of the sensor unit.
