A refrigerant evaporator includes an upstream tank portion for
distributing refrigerant into all laminated tubes of a core portion. The
upstream tank portion includes a first distribution passage for
distributing the refrigerant into the tubes in a direction parallel to a
tank longitudinal direction, a second distribution passage for
distributing the refrigerant from the first distribution passage into the
tubes in a tank width direction, and a communication passage through
which the refrigerant from the first distribution passage is supplied to
the second distribution passage after flowing in the tank longitudinal
direction.