Piezoelectric thin films have become increasingly significant in applications such as MEMS devices, wearable electronics, and lab-on-a-chip systems due to the miniaturization and integration of electronic devices. For piezoelectric thin films, even when an electric signal is applied in the thickness direction, greater deformation can often be observed in the in-plane direction, which is perpendicular to the electric field. Therefore, piezoelectric thin film devices are frequently designed using the transverse mode. As a result, it is crucial to evaluate piezoelectric thin films by measuring their transverse piezoelectric coefficient. This tutorial paper introduces a method for evaluating the effective transverse piezoelectric coefficient (e_31,f) of piezoelectric thin films using laser Doppler vibrometry (LDV). Additionally, the paper outlines a step-by-step procedure for measuring e31,f while using Bi_1/2Na_1/2TiO₃-based piezoelectric thin films as an example. This tutorial is expected to provide a practical and valuable method for measuring and analyzing the transverse piezoelectric properties, thereby supporting the development of new piezoelectric thin film materials.