An expansion valve for use in a refrigeration cycle, for throttling and expanding a refrigerant flowing from an upstream side and supplying the expanded refrigerant to an evaporator, the expansion valve comprising: a body having an inlet port through which a refrigerant is introduced from an upstream side, an outlet port through which the refrigerant is delivered to a downstream side, a valve hole through which the inlet port and the outlet port communicate with each other, an insertion hole formed coaxially with the valve hole, and a downstream-side passage (39, 339) intersecting at right angle with the valve hole and the insertion hole and through which the valve hole and the outlet port communicate with each other; a valve element configured to move toward and away from the valve hole to close and open a valve section; a drive unit provided on the body and configured to generate a drive force for opening or closing the valve section; a shaft slidably extending through the insertion hole, having a first end connected to the drive unit and a second end connected to the valve element through the downstream-side passage and the valve hole, and being configured to transmit the drive force of the drive unit to the valve element; and a wall member (360, 380) provided in the downstream-side passage (39, 339), wherein the downstream-side passage includes a small-diameter part to which the valve hole and the insertion hole are open, and a large-diameter part to which a pipe leading to the evaporator is connected, wherein the wall member (360, 380) is a plate member ( 360, 380) and has a shield part partially covering a downstream end of the small-diameter part, characterized in that the shield part has a height of 2 mm or larger in a radial direction of the small-diameter part from a projected position of an opening of the insertion hole at the downstream end of the small-diameter part and a width equal to or larger than a radius of the shaft within a range of the height, wherein the shield part of the wall member (360, 380) blocks the upper half of the downstream end of the small-diameter part, whereas the lower part is open and the plate member (360, 380) has a shape open in the radial direction toward a projected position of the valve hole, wherein an outer periphery of the plate member (360, 380) is fixed to an annular part formed at the boundary between the large-diameter part and the small-diameter part by a contact surface pressure in the radial direction, wherein the upper half of the plate member ( 360, 380) is fixed to the annular part at the positions of protrusions by the contact surface pressure wherein the lower half of the plate is open. a body having an inlet port through which a refrigerant is introduced from an upstream side, an outlet port through which the refrigerant is delivered to a downstream side, a valve hole through which the inlet port and the outlet port communicate with each other, an insertion hole formed coaxially with the valve hole, and a downstream-side passage (39, 339) intersecting at right angle with the valve hole and the insertion hole and through which the valve hole and the outlet port communicate with each other; a valve element configured to move toward and away from the valve hole to close and open a valve section; a drive unit provided on the body and configured to generate a drive force for opening or closing the valve section; a shaft slidably extending through the insertion hole, having a first end connected to the drive unit and a second end connected to the valve element through the downstream-side passage and the valve hole, and being configured to transmit the drive force of the drive unit to the valve element; and a wall member (360, 380) provided in the downstream-side passage (39, 339), wherein the downstream-side passage includes a small-diameter part to which the valve hole and the insertion hole are open, and a large-diameter part to which a pipe leading to the evaporator is connected, wherein the wall member (360, 380) is a plate member ( 360, 380) and has a shield part partially covering a downstream end of the small-diameter part, characterized in that the shield part has a height of 2 mm or larger in a radial direction of the small-diameter part from a projected position of an opening of the insertion hole at the downstream end of the small-diameter part and a width equal to or larger than a radius of the shaft within a range of the height, wherein the shield part of the wall member (360, 380) blocks the upper half of the downstream end of the small-diameter part, whereas the lower part is open and the plate member (360, 380) has a shape open in the radial direction toward a projected position of the valve hole, wherein an outer periphery of the plate member (360, 380) is fixed to an annular part formed at the boundary between the large-diameter part and the small-diameter part by a contact surface pressure in the radial direction, wherein the upper half of the plate member ( 360, 380) is fixed to the annular part at the positions of protrusions by the contact surface pressure wherein the lower half of the plate is open.