Acute psychological stress dynamically changes functional brain networks and induces negative emotional states including anxiety through altered release of neuromodulators such as catecholamines. The underlying neuronal mechanisms of stress responses have been extensively investigated, however they remain unclear. Recently, we found that the neurons in the claustrum are critically involved in stress-induced anxiety-like behaviors as determined by whole-brain activity mapping and DREADD-based pharmacogenetic manipulation of these neurons. Here, we show that pharmacogenetic activation of glutamatergic neurons in a subregion of the claustrum induces anxiety-like behaviors and leads to activation of several nuclei involved in stress response. Activation of the claustral glutamatergic neurons induced a tonic release of dopamine and noradrenaline in the medial prefrontal cortex. Pharmacological inhibition of the catecholamine signal attenuated the claustral activation-induced anxiety-like behaviors.　The present results suggest that glutamatergic neurons in the claustrum mediate stress-induced anxiety-like behaviors through modulating catecholamine release.