This study discusses the legal issues pertaining to data portability from the perspectives of both personal data protection and antitrust laws. Since legal challenges arise from the differences between antitrust law and data protection law, there is a need to define the legal position of data portability. My analysis is based on a review of these three topics: Is the right to data portability in the EU General Data Protection Regulation (GDPR) effective? (2) Should the right to data portability be legally regulated? and (3) Can the right be regulated from an antitrust perspective?What are indicated from the above discussions are: (1) the right to data portability in the GDPR is the first promising provision which has given rise to several issues—in particular the scope of the data, IT costs imposed on SMEs, and theoretical boundaries and enforcements based between data protection and antitrust laws—that warrant further examination; (2) if the controller-controller portability is called for, antitrust perspective broadly encompass the scope of data is preferred than data protection regulation; (3) combining data protection and antitrust perspectives into a single law would be difficult due to the differences of them; (4) when it comes to establish data portability scheme from antitrust perspective, data portability should be obliged depending on the kinds of platform.