It is crucial to select a good language task in fMRI to examine the language lateralization. We examined the concordances of 6 lateralization indices (LIs) using 4 language tasks. We confirmed that our previously developed LI, AveLI, showed a better concordance of index values across 4 tasks. Also, the verb generation task showed a better concordance across the 6 LIs than other tasks. In addition, this task showed a plausible ratio of rightward asymmetry (5 out of 16 left/both-hand preferred). Thus, we concluded to conduct the verb generation task and compute AveLI as a robust index of the language lateralization.