A charger (1) includes a connecting portion (5) provided in an upper case (3) of the charger. The connection portion (5) includes a pair of guide rails (6) to which a battery pack (40) is slidably attached. The charger further includes between the guide rails (6) a terminal block having various terminals (12–14) as well as a slide cover (21) linearly slidable in parallel with the direction in which the battery pack slides on the charger. Under normal operating conditions, the slide cover (21) is biased to a rear position in which the cover (21) is located over and protects a terminal block (11). When the battery pack (40) is set on the charger, the battery pack abuts and slides the slide cover to a forward position in which the terminal block (11) is exposed.