The accuracy of the phase fraction determined by time-of-flight neutron diffraction measurement at iMATERIA was verified by preparing model samples consisting of laminations of ferritic and austenitic stainless-steel sheets. Rietveld texture analysis, based on 132 diffractograms, was employed as the analysis method. The analyzed volume fractions of austenite agree with the prepared fractions (0.61-49.3 vol%) with a maximum error of only 5%, relative to the prepared fractions. This is due to the excellent fitting quality of the multi-diffractogram-based Rietveld refinement with consideration given to the textures of both the major and minor phases. Although the quality of the texture analysis for the austenite phase becomes poor, at\5 vol%, the consideration of the textures improves the accuracy of the phase fraction determination. Also described is how the textures affect the phase fractions, as determined by the conventional diffraction method. It is clearly shown that texture cannot be ignored in phase fraction analysis and, in turn, a reasonable consideration of the texture realizes precision in the analysis.