$Ca^{2+}$ transduces hormone and environmental signals to the $Ca^{2+}$ sensors and relays them to the downstream target effectors in cells. During the post-embryonic developmental process, auxin plays a critical role in maintaining the mitotically inactive status of the quiescent center (QC) and the root growth and development that follows. In this report, we demonstrate that $Ca^{2+}$ plays an important role in the maintenance of the QC, probably by regulating PIN1-mediated auxin transport. Perturbation of the intracellular $Ca^{2+}$ levels with chemicals that modify the $Ca^{2+}$ level decreases the endogenous auxin level and the size of the auxin maximum in the root tip and, at the same time, activates QC cell division and expansion. This decreased level of auxin is almost completely restored to the control level by the treatment of exogenous auxin. Interestingly, treatment with $Ca^{2+}$ level modifying chemicals significantly decreased the PIN1 expression in the root vasculature. Taken together, we suggest that balancing $Ca^{2+}$ homeostasis is one of contributing factors in establishing the proper auxin maximum in the root tip and maintaining the QC identity.