The sealed lead acid battery comprises a positive and/or negative electrode made of an active material added with porous polymer particles having an average pore diameter of 0.05 to 10 .mu.m and a particle size of 0.1 to 0.8 mm. The additive amount of the porous polymer particles ranges from 0.2 to 3 wt. %. The active material may be incorporated with porous particles of 0.3 to 5 wt. % previously impregnated therein with sulfric acid. The resultant sealed lead acid battery has a high energy density and is superior in a high efficient discharge characteristic, a cycle life characteristic and a low temperature characteristic.