An engine starting device comprising: a motor unit; a pinion gear unit(17,17a,17b,18,19) which rotates according to the rotation of an output rotation shaft driven by the motor unit; a pushing mechanism which moves the pinion gear unit(17,17a,17b,18,19) towards an engagement location of the pinion gear and an engine starting gear; and a bracket which includes a bracket main body unit which supports the motor unit and the pushing mechanism and a nose unit which extends from the bracket main body unit to a side opposite to the motor unit and rotatably bears a tip portion of the output rotation shaft on a side opposite to the motor unit, and which is attached to an engine side, wherein an engine is started by a rotation force of the motor unit through the pinion gear and the engine starting gear which are engaged with each other, the pinion gear unit (17,17a,17b,18,19) includes a rotation member which is spline-coupled to the output rotation shaft, is moved to a direction of the engine starting gear by the pushing mechanism, and rotates according to the rotation of the output rotation shaft, the pinion gear which is fit to the rotation member to be movable in the direction of the engine starting gear, moves with the rotation member if the pinion gear unit (17,17a,17b,18,19) is moved towards the engagement location by the pushing mechanism, is engaged with the engine starting gear, and rotates with the rotation member according to the rotation of the output rotation shaft, and an elastic member which pushes the pinion gear to be biased to the direction of the engine starting gear, a first stopper unit which restricts the movement of the rotation member by the pushing mechanism to the direction of the engine starting gear is provided on the output rotation shaft, a second stopper unit which restricts the movement of the pinion gear to the direction of the engine starting gear by pushing and biasing of the elastic member is provided on the rotation member, and the first stopper unit is positioned on a side opposite to the engine starting gear with respect to the second stopper unit. a motor unit; a pinion gear unit(17,17a,17b,18,19) which rotates according to the rotation of an output rotation shaft driven by the motor unit; a pushing mechanism which moves the pinion gear unit(17,17a,17b,18,19) towards an engagement location of the pinion gear and an engine starting gear; and a bracket which includes a bracket main body unit which supports the motor unit and the pushing mechanism and a nose unit which extends from the bracket main body unit to a side opposite to the motor unit and rotatably bears a tip portion of the output rotation shaft on a side opposite to the motor unit, and which is attached to an engine side, wherein an engine is started by a rotation force of the motor unit through the pinion gear and the engine starting gear which are engaged with each other, the pinion gear unit (17,17a,17b,18,19) includes a rotation member which is spline-coupled to the output rotation shaft, is moved to a direction of the engine starting gear by the pushing mechanism, and rotates according to the rotation of the output rotation shaft, the pinion gear which is fit to the rotation member to be movable in the direction of the engine starting gear, moves with the rotation member if the pinion gear unit (17,17a,17b,18,19) is moved towards the engagement location by the pushing mechanism, is engaged with the engine starting gear, and rotates with the rotation member according to the rotation of the output rotation shaft, and an elastic member which pushes the pinion gear to be biased to the direction of the engine starting gear, a first stopper unit which restricts the movement of the rotation member by the pushing mechanism to the direction of the engine starting gear is provided on the output rotation shaft, a second stopper unit which restricts the movement of the pinion gear to the direction of the engine starting gear by pushing and biasing of the elastic member is provided on the rotation member, and the first stopper unit is positioned on a side opposite to the engine starting gear with respect to the second stopper unit.