A lead cartridge adapted for storing leads and capable of being detachably connected to a lead feeding mechanism of a mechanical pencil to supply the leads one by one to the lead feeding mechanism, the mechanical pencil being provided with an interference part, the lead feeding mechanism being provided with a receiving part. The lead cartridge includes a tank part for storing the leads, a tip end connection part capable of being detachably fitted with the receiving part of the lead feeding mechanism, a lead port provided on a tip end side of the tank part to allow one of the leads in the tank part to pass from the tank part, and a swing cover arranged in the lead cartridge to be swingable between a closing position where the swing cover closes the lead port, and an opening position where the swing cover opens the lead port.