A starting device for a diesel engine that has an automatic stop control to stop fuel injection when a predetermined automatic stop condition is met, the starting device comprising: a plurality of fuel injection units configured to directly inject fuel in a plurality of cylinders (#1, #2, #3, #4) of the diesel engine, respectively; a plurality of glow plugs configured to generate heat upon receiving electricity to increase temperature of the cylinders (#1, #2, #3, #4) of the diesel engine, respectively; a starter motor configured to be driven to cause a crankshaft to rotate when the diesel engine starts running; and a control unit configured to control the fuel injection of the fuel injection units, electricity feeding to the glow plugs, and activation of the starter motor, characterized in that the control unit is configured to stop a piston of a predetermined cylinder (#1) among the plurality of cylinders (#1, #2, #3, #4) at a bottom dead center of a compression stroke and start the electricity feeding to the glow plug when the automatic stop control is performed, and thereafter, when the predetermined automatic stop condition is no longer met and the diesel engine is restarted, the control unit is also configured to drive the starter motor to cause the piston of the predetermined cylinder (#1) to move upward from the bottom dead center of the compression stroke, cause the fuel injection unit to inject the fuel in the predetermined cylinder in multiple injection stages after actuation of the starter motor is started so as to create a lean fuel-air mixture for main combustion in the predetermined cylinder (#1) and cause the fuel injection unit to inject fuel for ignition immediately before the piston of the predetermined cylinder (#1) reaches a top dead center so as to ignite the lean fuel-air mixture for main combustion. a plurality of fuel injection units configured to directly inject fuel in a plurality of cylinders (#1, #2, #3, #4) of the diesel engine, respectively; a plurality of glow plugs configured to generate heat upon receiving electricity to increase temperature of the cylinders (#1, #2, #3, #4) of the diesel engine, respectively; a starter motor configured to be driven to cause a crankshaft to rotate when the diesel engine starts running; and a control unit configured to control the fuel injection of the fuel injection units, electricity feeding to the glow plugs, and activation of the starter motor, characterized in that the control unit is configured to stop a piston of a predetermined cylinder (#1) among the plurality of cylinders (#1, #2, #3, #4) at a bottom dead center of a compression stroke and start the electricity feeding to the glow plug when the automatic stop control is performed, and thereafter, when the predetermined automatic stop condition is no longer met and the diesel engine is restarted, the control unit is also configured to drive the starter motor to cause the piston of the predetermined cylinder (#1) to move upward from the bottom dead center of the compression stroke, cause the fuel injection unit to inject the fuel in the predetermined cylinder in multiple injection stages after actuation of the starter motor is started so as to create a lean fuel-air mixture for main combustion in the predetermined cylinder (#1) and cause the fuel injection unit to inject fuel for ignition immediately before the piston of the predetermined cylinder (#1) reaches a top dead center so as to ignite the lean fuel-air mixture for main combustion.