Electric connection box and wire harness

A wire harness comprising:

• an electric wire;
• and
• an electric connection box, connected to the wire, that includes a casing having a plurality of walls that define an internal space portion and a cover side opening portion, the cover side opening portion in communication with the internal space portion, a plurality of electronic components housed in the internal space portion, and a cover that closes the cover side opening portion, wherein
• the casing is installed on an installation target such that a closing direction of the cover with respect to the cover side opening portion is a direction orthogonal to a vertical direction,
• the internal space portion is partitioned into a first housing region and a second housing region by a rib formed on the casing to extend in the vertical direction, in a width direction orthogonal to the vertical direction and the closing direction,
• the rib extends in an opening direction side which is a direction opposite to the closing direction, and includes a water passage section formed between the rig and a water passage wall opposite the rib in the width direction,
• of both end portions of the water passage section in the vertical direction, an upward side end portion communicates with a water collection section provided in the casing, and a downward side end portion communicates with an outside of the casing, and
• the water collection section includes a guide wall which overlaps an upward side end portion boundary which is a boundary located at an upward side end portion, of a boundary between the casing and the cover as viewed in the vertical direction, the guide wall being disposed on the upward side of the first housing region and the second housing region, and connected to the water passage wall.