The effects of $Ca^{2+}$ ion on the charge transfer(CT) interaction of $4-(C_9H_{19})C_6H_4O(CH_2CH_2O)_{40} [NP-(EO)_{40}]$ with iodine in aqueous solution were investigated by UV-visible spectrophotometer. Maximum absorption wavelengths to the CT interaction were in the vicinity of 390 nm, and by the addition of $Ca^{2+}$ ion shifted toward 370 nm. Above CMC, the intensity of the CT interaction by the addition of $Ca^{2+}$ ion were increased and then decreased. The increase in the intensity of CT band were attributed to the increase of the donor-acceptor overlap with iodine caused by the compactness of micelle in the presence of $Ca^{2+}$ ion. These phenomena suggest that the linear oxyethylene(EO) chains, relatively free to assume various configuration in aqueous solution, could form a pseudo-crown ether structures capable of forming complexes with $Ca^{2+}$ ion.