Strigolactone (SL) is an allelochemical attracting both symbiotic arbuscular mycorrhizal (AM) fungi and root parasitic plants and a plant hormone regulating shoot and root architecture. In general, nitrogen and phosphate deficiencies significantly promote SL production and exudation and suppress shoot branching in host plants of AM fungi. By contrast, although nutrient deficiencies suppressed the shoot branching of Arabidopsis thaliana, a non-host of AM fungi, the level of carlactone, one of major SLs in plant tissues, was not affected. In the present study, we demonstrate that nitrogen deficiency increases levels of SLs including carlactone in the basal part of shoots of A. thaliana.