Much of what we know about public service motivation comes from self-report measures. However, self-report questionnaires are vulnerable to social desirability bias due to respondents’ tendencies to answer in a more socially acceptable way. This is a problem as social desirability bias threatens the validity of the measure. This study investigates whether characteristics of national culture influence social desirability bias during surveys on public service motivation. In particular, the impact of social desirability bias is analyzed with two concerns in mind: construct validity and inference validity of public service motivation measures. Experimental survey research (list experiment) is conducted to examine the magnitude of social desirability bias and its associations with national cultures in four countries: Japan, Korea, the Netherlands, and the United States. The results show that respondents in both collectivistic countries (Japan and Korea) and individualistic countries (the Netherlands and the United States) are likely to over-report answers on items of public service motivation, although the magnitude and pattern of this bias is stronger and more consistent in collectivistic countries. This study also finds a strong possibility of a moderator effect in correlational analyses in collectivistic countries, but it is doubtful this effect is present in individualistic countries. Overall, we suggest that the effects of social desirability bias should be investigated in public service motivation research, and social desirability bias should be controlled for in future research.