An idling stop device installed in a vehicle includes a microcomputer, a detector, a storage, and a controller. The microcomputer automatically stops an engine of the vehicle when a prescribed stopping condition is satisfied, and automatically activates a starter motor of the engine when a prescribed activating condition is satisfied. The detector detects whether a drive voltage of the microcomputer, which is obtained by dropping a voltage of a battery of the vehicle is less than a threshold value. The storage stores, irrespective of a state of the microcomputer, information indicating that the detector has detected that the drive voltage is less than the threshold value. The controller drops an increasing speed of a current for driving the starter motor when the microcomputer activates the stator motor under the condition that the information is stored in the storage.