A refrigerant evaporator is provided in which a liquid refrigerant can be evenly distributed to a plurality of refrigerant tubes connected to first and second tanks in a U-turn block to improve heat-exchange performance. In the refrigerant evaporator, one of a plurality of blocks into which a refrigerant supply channel is divided is a U-turn block where a refrigerant flows into one of the first and second tank portions of an upper tank in a direction along a partition wall, flows into the other tank portion, and is distributed and flows from the first and second tank portions into a plurality of refrigerant tubes. The partition wall partitioning the first and second tank portions of the upper tank has a plurality of refrigerant-distributing holes arranged in a longitudinal direction of the partition wall in the U-turn block so that the first tank portion communicates with the second tank portion.