It is increasingly common to upload photographs on the Internet of sports practices carried out. However, this behavior can be related to smartphone addiction, which has become a global problem. In turn, the intensive use of the Instagram social network has begun to be linked to addictive behaviors on mobile devices. The purposes of this paper were to analyze the Instagram usage habits of future primary school teachers, to determine the influence of sociodemographic factors on intensive Instagram use and smartphone addiction, and to determine the influence of intensive Instagram use on smartphone addiction. For this purpose, a transversal design was adopted where two standardized scales were applied to a sample of university students of the Primary Education Degree of the University of Granada, Spain (n = 385). The results showed that the type of image most uploaded to this social network was the selfie, well above sport. Furthermore, the structural equation model highlighted the significant influence of the intensive use of Instagram and smartphone addiction. Finally, the implications and findings of this study are discussed, highlighting the importance of generating healthy habits regarding the use of technology.