In determining the mechanism of an earthquake source, two main and auxiliary planes are identified. Proving which plane is really a failure plane has always been of interest to seismologists. Determining these nodal-planes helps us to understand the geodynamical model and the stress field in the region. One way to detect the failure plane of an earthquake is to analyze its aftershocks. In this study, we determine the fracture plane of the Qotur-doublet earthquakes, by analyzing the spatial distribution of aftershocks. The Qotur doublet-earthquakes with magnitudes MN 5.7, 5.9 occurred in 2020 February 23 in western Aarbaijan province near the Iran-Turkey border, and was followed by many aftershocks. We relocated the aftershocks by using the seismic stations located in Iran and Turkey. The general pattern of relocated aftershocks distribution shows a seismic zone covering an area of approximately 16×10 km2. The cross-sections through aftershock locations show that the focal depths decrease toward the southeastern part of the region, and deeper-aftershocks are located in the northwestern part. This observation suggests that the causative fault of the Qotur doublet-earthquakes dip toward northwest with striking along the southeast-northwest.