We study the equations of state (EOS) of boson stars using two kinds of interaction based on the Klein-Gordon equation of complex scalar field coupled with gravitation and U(1) gauge field in semi-classical manner, i.e. one with repulsive interaction mediated by massive vector mesons (1/2mv2AμAμ) and one with further addition of self-interacting scalar field terms [-1/2γ(Φ∗Φ)2-13κ(Φ∗Φ)3]. The equations of state are obtained from the non-zero energy-momentum tensor of matter's Lagrangian. In our formulations, the equations of state are calculated directly using curved space-time and indirectly using boosted flat space-time frame-works. For the homogeneous assumption and the case of photon as a mediator, we found that the equations of state do not fulfill the causality principle. So, from those analytic formulations, we obtain the equations which can be solved numerically. Therefore, the characteristics of boson stars of two kinds of self-interaction can be investigated.