To provide an oar 10 capable of keeping the strength of the joint part 6 between an oar shaft 1 and an oar blade 2 and the weight of the oar while reducing a diameter in the outer shape of the shaft in order to reduce air resistance.

In the oar 10 for a scull provided with the oar blade 2 on one end part of the oar shaft 1, the length of the joint part 6 of the oar shaft and the oar blade is ≥80 mm and ≤260 mm or the cross sectional shape of the oar shaft within the joint part is turned to a different diameter cross section. In the oar for a sweep provided with the oar blade on one end part of the oar shaft, the length of the joint part of the oar shaft and the oar blade is ≥90 mm and ≤270 mm or the cross sectional shape of the oar shaft of the joint part is turned to the different diameter cross section.