VEHICLE BATTERY PACK

There is provided a vehicle battery pack (10) including: a battery case (20) in which a battery module (11) is built; an electrical component (13) configured to convert electric power from the battery module (11); a duct (50) through which an air for cooling flows; a cooling fan (12) configured to circulate the air to the duct (50); and a housing (30) which houses the battery case (20), the electrical component (13), and the duct (50). The battery case (20) includes: a first vertical wall (20A) extending in a first direction; a second vertical wall (20B) extending in a second direction orthogonal to the first vertical wall (20A); and a corner portion (20C) where the first vertical wall (20A) and the second vertical wall (20B) intersect. The electrical component (13) is disposed on a lateral side of the battery case (20) in a manner facing the first vertical wall (20A) in the second direction. The duct (50) includes: an upstream duct (51) connected to the cooling fan (12); and a downstream duct (52) that communicates with a discharge port (51A) formed on the upstream duct (51) and that is configured to guide the air, which is guided from the upstream duct (51) through the discharge port (51A), to the battery case (20) and the electrical component (13). The downstream duct (52) includes: a first downstream duct portion (60) that extends from the corner portion (20C) along the first vertical wall (20A), the first downstream duct portion (60) having a downstream end that communicates with the electrical component (13); a second downstream duct portion (70) that extends from the corner portion (20C) along the second vertical wall (20B), the second downstream duct portion (70) having a downstream end that communicates with the battery case (20); and a downstream duct corner portion connected to the first downstream duct portion (60) and the second downstream duct portion (70) on a lateral side of the corner portion (20C). And the discharge port (51A) is disposed across one of the first downstream duct portion (60) and the second downstream duct portion (70), and across the downstream duct corner portion.