To provide a manufacturing method of an enclosed lead acid storage battery which enables to reduce greatly the manufacturing cost and has an excellent and stable battery performance.

This is a manufacturing method of an enclosed lead acid storage battery in which a solution of granular silica dispersed in the dilute sulfuric acid is filled from the upper side filling opening of a battery of which the inner face is provided with a filter in the whole inner face of the battery jar except the filling opening, and the excess dilute sulfuric acid is discharged from the discharge opening which is provided on the same surface as the filling opening, hence filling of granular silica and the filing of sulfuric acid are made simultaneously.