An electrical junction box comprising: a casing containing a circuit assembly therein; a connector housing disposed on a bottom of the casing and adapted to be coupled to a mating connector; a plurality of terminal metals connected to the circuit assembly and passing through a wall of the connector housing to be drawn into the connector housing; and a waterproof cover formed individually from the casing and disposed in the casing. The waterproof cover includes a first waterproof wall for covering a space above adjacent terminal metals, a second waterproof front wall and second waterproof side walls for partitioning a space between the adjacent terminal metals and a side wall of the casing.