A ceiling concealed air-conditioning apparatus comprising: a body containing a heat exchanger and a fan and including an opening port at a bottom; a decorative panel disposed below the body, the decorative panel being configured to cover a periphery of the opening port of the body; and a suction grille including, on one edge thereof, a rotary shaft that can be attached to the decorative panel, the suction grille being configured to cover the opening port of the body so as to allow the opening port to be opened, wherein the suction grille includes: a locking element mounted on a rear side of the suction grille so that it can slide and configured to be locked with the decorative panel; plate springs (31a, 31b) on respective sides of the locking element perpendicular to a sliding direction of the locking element, the plate springs (31a, 31b) extending vertically in opposite directions to each other; and spring supports (15a, 15b) provided to the suction grille and configured to support both end faces of the respective plate springs (31a, 31b) at different positions, the plate springs (31a, 31b) of the locking element include a long plate spring and a short plate spring having different lengths, and the long plate spring and the short plate spring are placed such that the long plate spring is engaged first when the suction grille is attached to the decorative panel. a body containing a heat exchanger and a fan and including an opening port at a bottom; a decorative panel disposed below the body, the decorative panel being configured to cover a periphery of the opening port of the body; and a suction grille including, on one edge thereof, a rotary shaft that can be attached to the decorative panel, the suction grille being configured to cover the opening port of the body so as to allow the opening port to be opened, wherein the suction grille includes: a locking element mounted on a rear side of the suction grille so that it can slide and configured to be locked with the decorative panel; plate springs (31a, 31b) on respective sides of the locking element perpendicular to a sliding direction of the locking element, the plate springs (31a, 31b) extending vertically in opposite directions to each other; and spring supports (15a, 15b) provided to the suction grille and configured to support both end faces of the respective plate springs (31a, 31b) at different positions, a locking element mounted on a rear side of the suction grille so that it can slide and configured to be locked with the decorative panel; plate springs (31a, 31b) on respective sides of the locking element perpendicular to a sliding direction of the locking element, the plate springs (31a, 31b) extending vertically in opposite directions to each other; and spring supports (15a, 15b) provided to the suction grille and configured to support both end faces of the respective plate springs (31a, 31b) at different positions, the plate springs (31a, 31b) of the locking element include a long plate spring and a short plate spring having different lengths, and the long plate spring and the short plate spring are placed such that the long plate spring is engaged first when the suction grille is attached to the decorative panel.