A toner supplying device comprising: a toner container that is tubular, includes a spiral groove at an outer circumferential face of the toner container, a toner discharge opening at one end in a longitudinal direction of the toner container, and a depression at the other end in the longitudinal direction, and is rotationally driven to convey toner contained in the toner container along the spiral groove in the longitudinal direction to discharge the toner from the toner discharge opening; a toner container holder having one end and another end; a rotational driving unit that engages with the one end of the toner container to rotationally drive the toner container to cause the toner container to discharge the toner contained therein; an interior portion for inserting and installing the toner container is arranged at the other end of the toner container holder; a projection (52, 152) provided at the interior portion at which the toner container is installed, and the toner supplying device supplying the toner discharged from the toner container to a developing device, wherein the projection (52, 152) is formed to fall in the depression of the toner container, wherein the projection (52; 152) has an inclined face (52a; 152a) and the inclined face (52a; 152a) is inclined so as to gradually increase in the projection amount toward downstream in the rotational direction of the toner container and is formed in a curve, wherein the toner supplying device further comprises: a vibration intensity adjusting unit (153, 300) that adjusts an intensity of vibration generated with the projection and the depression, characterized in that the vibration intensity adjusting unit (153, 300) adjusts the projection amount of the projection by elastically displacing the projection. a toner container that is tubular, includes a spiral groove at an outer circumferential face of the toner container, a toner discharge opening at one end in a longitudinal direction of the toner container, and a depression at the other end in the longitudinal direction, and is rotationally driven to convey toner contained in the toner container along the spiral groove in the longitudinal direction to discharge the toner from the toner discharge opening; a toner container holder having one end and another end; a rotational driving unit that engages with the one end of the toner container to rotationally drive the toner container to cause the toner container to discharge the toner contained therein; an interior portion for inserting and installing the toner container is arranged at the other end of the toner container holder; a projection (52, 152) provided at the interior portion at which the toner container is installed, and the toner supplying device supplying the toner discharged from the toner container to a developing device, wherein the projection (52, 152) is formed to fall in the depression of the toner container, wherein the projection (52; 152) has an inclined face (52a; 152a) and the inclined face (52a; 152a) is inclined so as to gradually increase in the projection amount toward downstream in the rotational direction of the toner container and is formed in a curve, wherein the toner supplying device further comprises: a vibration intensity adjusting unit (153, 300) that adjusts an intensity of vibration generated with the projection and the depression, characterized in that the vibration intensity adjusting unit (153, 300) adjusts the projection amount of the projection by elastically displacing the projection.