Provided are a method of fabricating a 3-dimensional transistor sensor and the sensor and a sensor array thereof. The method of fabricating the 3-dimensional transistor sensor includes forming an insulating layer on a silicon substrate, forming a silicon layer on the insulating layer and forming a 3-dimensional silicon fin by etching the silicon layer, forming a source area and a source electrode at one end of the silicon fin, forming a drain area and a drain electrode at the other end the silicon fin, and forming a gate area at a center of the silicon fin, surrounding three surfaces of a gate with a gate insulating layer, forming a sensing gate layer configured to surround a portion of the gate insulating layer, and sealing an upper portion of the gate insulating layer excluding the sensing gate layer.