The role of the dipole-dipole (DD) interaction in organic molecular antiferromagnet MOTMP is elucidated. The anisotropy energy due to the DD interaction can explain well the experimental values of the spin-flop field and the saturation field along each crystal axis if we use the nearest neighbor (n.n.) interchain exchange coupling J(c) = -0.0087 K and if we introduce small anisotropy for the intrachain exchange coupling. The uniform magnetic susceptibility in the paramagnetic state has been calculated by taking into account the DD interaction on the basis of the dynamical correlated-effective-field approximation. The observed susceptibility are well reproduced by assuming the n.n. intrachain exchange coupling J(a)=0.45 K and the next n.n. interchain exchange coupling J(b)=0 K. The Neel temperature T-N is determined to be 0.15 K, which agrees with the observation.