Stomatal movement is an important topic in plant water metabolism. Inorganic ions in guard cells play a key role in responding to extracellular stimuli and adjusting turgor pressure as a secondary messenger (Ca²⁺) or an osmotic solute (K⁺, Cl^–). Ion channels in plasma and vacuole membranes are targets of various stimuli that modulate stomatal aperture; they are important components in charge of ion transport. Here, we briefly review research progress into ions and ion channels in guard cells.