It has been investigated about Electron Spin Resonance spectra of Sour-sop Leaves (Annona muricata L) extract compound from Kupang distric. The aim of this research is to determine the amplitude response and sensitivity of sour-sop leaves extract compound to X-ray radiation. In this research, sour-sop leaves extract compound is obtained by maceration extraction method using n-Hexane and ethanol pro analysis solvent, then its extract is evaporated. Furthermore, it is conducted annealing process to obtain its powder. Samples of sour-sop leaves extract compound were weighed 0.2 grams then be irradiated with X-rays voltage of 70 kV - 85 kV at RSU Prof. W.Z. Yohanes Kupang. The dose rate were obtained in this research is from 8,69 x 10-8 Gy/hour to 9,91 x 10-8 Gy/hour. Subsequently, these samples was calibrated using an Electron Spin Resonance Spectroscopi in Physics Laboratory, Science and Technique Faculty - Nusa Cendana University . Based on research data analysis result, amplitude response and sensitivity of sour-sop leaves extract are obtained 9,45 Volt/kg - 10,8 Volt/kg and 9,20 x 10 -9 Gy.kg/h.Volt - 9,22 x 10 -9 Gy.kg/h.Volt respectively. Amplitude response of sour-sop leaves extract compound is linear to the absorbtion dose rate and its sensitivity is relatively constant to dose rate. Based on amplitude response and sensitivity value, sour-sop leaves extract compound is potential to use as an alternative active material in dosimeter for medical radiography purposes.