Magnesiumphthalocyanine (MgPc) is a blue pigment whose X-phase is known to exhibit an intense near-IR absorption. The near-IR absorption of MgPc has been investigated from the standpoints of exciton coupling effects on the basis of the crystal structure. Two kinds of six-coordinate MgPc complexes were grown from solution and their structures were analyzed: MgPc/(H₂O)₂·(N-methyl-2-pyrrolidone)₂ (crystal 1) and MgPc/(2-methoxyethanol)2 (crystal 2). In both crystals, two oxygen atoms of the solvent molecule are coordinated to the central Mg atom above and below the molecular plane, forming a distorted sp³d² octahedron. Of these crystals, only crystal 1 exhibits a near-IR absorption whose spectral shape is quite similar to that of the X-phase. In addition, the X-phase is also found to contain two water-molecules in the normal ambient atmosphere. The near-IR absorption in both crystal 1 and the X-phase can reasonably be interpreted as arising from exciton coupling effects based on the molecular arrangement of MgPc/(H₂O)₂.