ELECTRICITY STORAGE SYSTEM

The present invention provides an electric storage system having a structure capable of easily mounting a submersion-prevention vessel incorporating a cell module in a housing case. The present invention provides an electric storage system comprising a top-opened box-shaped submersion-prevention vessel accommodating a cell module including a plurality of battery cells and a mounting base for mounting the submersion-prevention vessel by inserting the vessel from a front side to a rear side, wherein a protruding portion is provided in a lower portion of at least one outer wall surface of the submersion-prevention vessel; a fixing member for fixing the protruding portion is provided on the rear side of a top surface of the mounting base for mounting the submersion-prevention vessel; and a guide member that is formed so as to gradually expand in width toward a side opposite to a direction of slidably moving when mounting the submersion-prevention vessel and that positions the submersion-prevention vessel is provided on both end portions of the fixing member.