This paper demonstrates charge order is important in dimerized β- and κ-phase organic conductors similar to the uniform θ- and α-phase conductors. Here the magnitude of the dimerization represents the deviation from the ideal triangular lattice in analogy with the anisotropy in the θ phase. Since the ratio of the intradimer transfer integral to the interdimer transfer integral is as large as ∼2.6, these dimerized phases lead to a dimer Mott insulator, whereas the Coulomb repulsion is closer to the triangular lattice because the ratio of the intradimer Coulomb repulsion to the interdimer Coulomb repulsion is comparatively small (∼1.7). Accordingly, in the static-limit calculation, non-stripe charge order with threefold periodicity appears between the uniform and the stripe phases, and the analogy with the θ phase suggests the first-order nature of the metal-insulator transition.