An electric work vehicle comprising: rear wheels; a work implement; and a battery pack mounted on a vehicle body and arranged rearward of a central axis of the rear wheels and supplying electric power for driving the rear wheels and the work implement, the battery pack comprising: a battery unit; a casing housing the battery unit; a circulation fan mounted in an inner space of the casing; and an air guide provided in the casing and configured to direct cooling air produced by the circulation fan to the battery unit, characterized in that the casing includes a rectangular first casing having a first inner space housing the battery unit, a rectangular second casing smaller in size than the first casing, the second casing projecting upward from a top surface of the first casing as viewed from a lateral side of the vehicle body, the second casing having a second inner space housing the circulation fan, and a battery control unit connected to the battery unit, the battery control unit being housed in the second inner space, a fan opening and a return opening are formed in a boundary between the first casing and the second casing, the first inner space communicating with the second inner space via the fan opening and the return opening to flow the cooling air between the first inner space and the second inner space; and the first inner space and the second inner space are tightly closed to the outside, to the extent that the amount of ambient air introduced from the outside into the first inner space and the second inner space is substantially reduced. rear wheels; a work implement; and a battery pack mounted on a vehicle body and arranged rearward of a central axis of the rear wheels and supplying electric power for driving the rear wheels and the work implement, the battery pack comprising: a battery unit; a casing housing the battery unit; a circulation fan mounted in an inner space of the casing; and an air guide provided in the casing and configured to direct cooling air produced by the circulation fan to the battery unit, characterized in that the casing includes a rectangular first casing having a first inner space housing the battery unit, a rectangular second casing smaller in size than the first casing, the second casing projecting upward from a top surface of the first casing as viewed from a lateral side of the vehicle body, the second casing having a second inner space housing the circulation fan, and a battery control unit connected to the battery unit, the battery control unit being housed in the second inner space, a fan opening and a return opening are formed in a boundary between the first casing and the second casing, the first inner space communicating with the second inner space via the fan opening and the return opening to flow the cooling air between the first inner space and the second inner space; and the first inner space and the second inner space are tightly closed to the outside, to the extent that the amount of ambient air introduced from the outside into the first inner space and the second inner space is substantially reduced. a battery unit; a casing housing the battery unit; a circulation fan mounted in an inner space of the casing; and an air guide provided in the casing and configured to direct cooling air produced by the circulation fan to the battery unit, characterized in that the casing includes a rectangular first casing having a first inner space housing the battery unit, a rectangular second casing smaller in size than the first casing, the second casing projecting upward from a top surface of the first casing as viewed from a lateral side of the vehicle body, the second casing having a second inner space housing the circulation fan, and a battery control unit connected to the battery unit, the battery control unit being housed in the second inner space, a fan opening and a return opening are formed in a boundary between the first casing and the second casing, the first inner space communicating with the second inner space via the fan opening and the return opening to flow the cooling air between the first inner space and the second inner space; and the first inner space and the second inner space are tightly closed to the outside, to the extent that the amount of ambient air introduced from the outside into the first inner space and the second inner space is substantially reduced.