An electrical connection box comprising: a positive electrode side busbar connected to a positive electrode of a battery; a negative electrode side busbar connected to a negative electrode of the battery; and a case in which the positive electrode side busbar and the negative electrode side busbar are accommodated, wherein the case includes a bottom wall, a circumferential wall erected from the bottom wall, and a partition wall erected from the bottom wall, the circumferential wall is provided with a pair of wall portions (51, 52) facing each other, and the partition wall is provided between the pair of wall portions (51, 52), a positive electrode side busbar accommodation area in which the positive electrode side busbar is accommodated and a negative electrode side busbar accommodation area in which the negative electrode side busbar is accommodated are partitioned over the entire circumference by the partition wall and the circumferential wall, the partition wall is a waterproof partition wall that partitions the positive electrode side busbar accommodation area in which the positive electrode side busbar is accommodated and the negative electrode side busbar accommodation area in which the negative electrode side busbar is accommodated, the case includes a plurality of busbar attachment portions erected from the bottom wall on both sides of each of the positive electrode side busbar and the negative electrode side busbar, and a height of each of the plurality of the busbar attachment portions is slightly higher than a thickness of the positive electrode side busbar or the negative electrode side busbar and is lower than a height of the circumferential wall and the partition wall. a positive electrode side busbar connected to a positive electrode of a battery; a negative electrode side busbar connected to a negative electrode of the battery; and a case in which the positive electrode side busbar and the negative electrode side busbar are accommodated, wherein the case includes a bottom wall, a circumferential wall erected from the bottom wall, and a partition wall erected from the bottom wall, the circumferential wall is provided with a pair of wall portions (51, 52) facing each other, and the partition wall is provided between the pair of wall portions (51, 52), a positive electrode side busbar accommodation area in which the positive electrode side busbar is accommodated and a negative electrode side busbar accommodation area in which the negative electrode side busbar is accommodated are partitioned over the entire circumference by the partition wall and the circumferential wall, the partition wall is a waterproof partition wall that partitions the positive electrode side busbar accommodation area in which the positive electrode side busbar is accommodated and the negative electrode side busbar accommodation area in which the negative electrode side busbar is accommodated, the case includes a plurality of busbar attachment portions erected from the bottom wall on both sides of each of the positive electrode side busbar and the negative electrode side busbar, and a height of each of the plurality of the busbar attachment portions is slightly higher than a thickness of the positive electrode side busbar or the negative electrode side busbar and is lower than a height of the circumferential wall and the partition wall.