The aim of the study is to develop a "Self-Efficacy Scale for Argumentation" (SEAS). The participants of the study consisted of 879 pre-service elementary teachers. In order to examine construct validity of SEAS, exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were utilized. The initial solution of the EFA results revealed that three-factor structure consisting of 24 items called "Effort", "Confidence" and "Determination" for argumentation was obtained. Since the factor-item correlations were not significant for the "Determination" scale (p>0.05), the two-factor structure consisting of the "Effort" and "Confidence" for argumentation was validated by the repeated CFA. The accepted fit indices for the repeated CFA results were X[supercript 2] /sd=2.62; p<0.001; RMSEA=0.07; S-RMR=0.05; NFI=0.86; CFI=0.91; GFI=0.87. The moderate and significant correlation coefficients between the scores of the SEAS with the scale of "Inquiry Learning Skills Perception in Science" (Taskoyan, 2008) proved the criterion validity of the SEAS. The test-retest reliability of the SEAS was found to be moderate and significant. The internal consistency of SEAS is 0.93. Finally, a significant difference between the upper and lower groups means that the item discrimination of the SEAS is high. [This manuscript was presented at the 2nd International Conference on Science, Mathematics, Entrepreneurship and Technology Education, 19-22 November, 2020, Bursa, Turkey.]