One of the crucial issues for successful technology-enhanced out-of-class language learning (OCLL) is the learners' continuance intention to use technology. Considering the strong mutual relationship between learners' intention and motivation, the present study extended the technology acceptance model (TAM) with the self-determination theory (SDT) to investigate Japanese EFL learners' intention to use learning technologies for OCLL. The study was conducted in a technology-enhanced OCLL environment using a web-based e-portfolio system. The hypothesised model included two principal antecedents of behavioural intention introduced by TAM - perceived usefulness and perceived ease of use - in addition to the three psychological needs for competence, autonomy, and relatedness introduced by SDT. Path analysis was conducted to find the multivariate relationships between the constructs in the model based on the collected data from 162 Japanese EFL learners. The results indicated that SDT determinants could significantly predict perceived usefulness and perceived ease of use, among which perceived competence was the most influential factor. Furthermore, perceived usefulness highly influenced the learners' intention to continue technology-enhanced OCLL, which in turn influenced their actual usage of the system.