There are various factors that may affect user experience (UX) on a product. In this study, we investigate the attachment factor in UX over a time span. In this paper, we firstly discuss our view on attachment and UX from an interdisciplinary perspective, by taking iPhone as our case study. We describe the design of an experiment based on a time span sheet and take account into account the attachment factor in UX. We further reports the experiment results based on data collected from 36 subjects (among them 20 are iPhone users), and discuss our observations from the statistical analysis. The experiment result shows that there exists interrelation between attachment factor and UX, and the attachment of users to a specific product is created and strengthened while using it for a long time.