A steam ironing apparatus includes a base containing a device for producing steam connected by a pipe to a smoothing accessory including a hole for emitting steam. The base includes a coat hanger for hanging a garment and mounted to pivot on the base about an axis by a pivot connection. The hanger is prevented from rotating by a locking device. The locking device includes a control member movable by the user from an unlocked position that allows the hanger to rotate freely, into a locked position in which the hanger is prevented from rotating. The movement of the control member from the unlocked to the locked position causes the movement and/or deformation of a braking element from an initial position that allows free rotation of the pivot connection, towards a braked position in which the braking element is kept pressed against an element to prevent the hanger from rotating.