This paper presents a new sensing technique based on metamaterial for detecting sub-millimeter surface cracks. The sensing principle is based on shift in resonance frequency, due to loss or change in electromagnetic field perturbed around the electrically small resonator, i.e. metamaterial structure. The sensor is simple, small inexpensive and sensitive when compared to other crack detecting sensors. The sensing part or resonator part is etched out from the ground plane of a micro strip transmission line design. This sensor operates at a frequency of 2.5GHz and detects crack size around 50μm to 400μm. © Research India Publications.