Chargeable electric instrument of watertight housing capable of still discharging abnormally generated gas or liquid from built-in storage battery. The instrument includes a gas discharging valve means provided at an open end of a storage-battery casing, a cap means fixed to the casing for liquid-tightly enclosing the open end and valve means, a charge current feeding means provided in an end part of the housing, and a gas or liquid flow-path means made through the cap means and housing while preventing an entry of any fluid from the exterior, whereby any explosive gas internally generated can be effectively discharged through the valve, cap and flow-path means to the exterior.