With the recent rapid growth of the high-tech industry and its emergence as a new growth engine for firms, numerous studies explaining the adoption process of high-tech products and services have been reported in the consumer behavior field. However, causal research on multidimensional factors considering both the initial adoption stage and the post-adoption stage of high-tech products remains limited. Accordingly, this study developed and empirically tested an integrated model of consumer adoption and post-adoption behavior for high-tech products. For the empirical analysis, a longitudinal survey was conducted to analyze consumers' pre-adoption and post-adoption behaviors. First, a primary survey was administered to consumers intending to purchase smartphones at mobile carrier retail stores in Seoul and the metropolitan area. Subsequently, with a time interval of approximately 30 days, a secondary survey was administered to respondents who had completed the first questionnaire. The analysis results showed that relative advantage, aesthetics, and social image had significant effects on adoption intention. Adoption intention had a positive effect on adoption behavior, and adoption behavior had a significant effect on relationship investment. Relationship investment had significant effects on switching costs and emotional attachment. Switching costs had a significant effect on continuance intention. Emotional attachment had significant effects on both switching costs and continuance intention. Based on these empirical findings, marketing implications for high-tech firms were presented.