Salicylic acid (SA) plays a crucial role in plant immunity. However, its function in plant devel-opment is poorly understood. The quiescent center (QC), which maintains columella stem cells (CSCs) in the root apical meristem and typically exhibits low levels of cell division, is critical for root growth and development. Here, we show that the Arabidopsis thaliana SA overaccumulation mutant constitutively acti-vated cell death 1 (cad1), which exhibits in-creased cell division in the QC, is rescued by additional mutations in genes encoding the SA biosynthetic enzyme SALICYLIC ACID IN-DUCTION DEFFICIENT2 (SID2) or the SA re-ceptor NONEXPRESSER OF PR GENES1 (NPR1), indicating that QC cell division in the cad1 mutant is promoted by the NPR1-dependent SA signaling pathway. The applica-tion of exogenous SA also promoted QC cell division in wild-type plants in a dose-dependent manner and largely suppressed the expression of genes involved in QC maintenance, including those encoding the APETALA2 (AP2) tran-scription factors PLETHORA1 (PLT1) and PLT2, as well as the homeodomain transcription factor WUSCHEL-RELATED HOMEOBOX5 (WOX5). Moreover, we showed that SA promotes reactive oxygen species (ROS) production, which is necessary for the QC cell division phenotype in the cad1 mutant. These results provide insight into the function of SA in QC maintenance.