In the digital age, social media has become a transformative force, reshaping consumer interactions with products, brands, and services. This essay delves into the intricate interplay between cultural factors and consumer behavior within the realm of social media, focusing on a cross-cultural comparative study between Japan and the United States. The study explores consumer behavior through the lens of psychological, social, and cultural influences. It investigates how psychological aspects like motivation and attitudes, as well as social factors such as family and reference groups, are intertwined with cultural dimensions to shape consumer preferences. This essay employs a comparative approach, focusing on Japan and the United States as distinct cultural contexts. By applying Hofstede's cultural dimensions model, it dissects differences in individualism, power distance, masculinity-femininity, long-term orientation, uncertainty avoidance, and indulgence-restraint. The findings reveal significant disparities in consumer behavior on social media between these two nations. Cultural factors profoundly impact user engagement, content resonance, and purchasing decisions on social media platforms. This study underscores the indispensable role of cultural factors in molding consumer behavior in the digital age. Understanding and adapting to cultural nuances are imperative for marketers seeking to effectively engage and influence diverse global audiences through social media channels.