Disclosed herein is a battery management system for controlling the operation of a middle-or large-sized battery pack, the battery management system comprising: a battery management system printed circuit board (BMS PCB) comprising a circuit and elements for controlling the operation of the battery pack; a connector attached to one side of the BMS PCB; a housing including a housing body for receiving the BMS PCB while partially exposing the connector and a cover for covering the housing body, the cover is coupled to the housing body while the cover is disposed on the housing body; and a waterproofing member interposed between the housing body and the cover, constituting the housing, such that the waterproofing member is in tight contact with the interface between the housing body and the cover, the waterproofing member being constructed in a structure to be coupled at coupling regions of the housing body and the cover. The battery management system according to the present invention is constructed in a structure in which moisture is prevented from permeation into the housing of the battery management system in a high-temperature, high-humidity environment. Consequently, the present invention has the effect of preventing the damage to and the corrosion of the BMS PCB, and therefore, improving the reliability of the battery pack and increasing the service life of the battery pack.