To obtain the same continuous spot weldability as in case of sufficient cooling water, even if its flow rate is less, in an electrode for resistance spot welding of an aluminum based material, and to efficiently cool the electrode in an environment where cooling water is likely to be insufficient.

The electrode 1 for resistance spot welding of an aluminum based material is constituted of an electrode material whose electric conductivity is 97 IACS% or higher, and whose high temperature hardness property in terms of Vickers hardness is Hv80 or higher at 200°C or below and Hv30 or lower at 400°C or above. In this case, as a concentrated cooling means for only the center of the inner part of the electrode, a small cooling hole 5 is formed at the tip end of the cooling hole 4 inside the electrode; the diameter d5 of this small cooling hole 5 is smaller than that of a projection self-formed by continuous spot welding or that of a preformed pin-shaped projection.