A fluid valve comprising: a housing having a spool hole, a feeding port and a discharge port, the spool hole being in communication with a drain port, the feeding port being configured to receive a hydraulic fluid fed thereto, and the discharge port being configured to discharge the hydraulic fluid; and a spool movably provided in the spool hole, wherein the spool has: a connection recess defined in an outer surface of the spool, the connection recess being configured to establish communication between the feeding port and the discharge port; and a liaison channel establishing communication between the connection recess and the drain port, and wherein, within the liaison channel, a flow channel is formed between the spool hole and the outer surface of the spool, the flow channel serves as a filter to stop foreign matter from entering into the drain port, wherein a radial width of the flow channel is sized to inhibit passage of foreign matter of a desired size, wherein the flow channel constitutes a given part of a gap formed between the spool hole and the outer surface of the spool, and characterized in that the flow channel has a greater radial width than a remaining part of the gap formed between the spool hole and the outer surface of the spool since a reduced diameter portion is formed directly in the spool and the flow channel is formed between an outer surface of the reduced diameter portion and an inner surface of the spool hole, or since an increased diameter portion is formed directly in the spool hole and the flow channel is formed between an inner surface of the increased diameter portion and the outer surface of the spool. a housing having a spool hole, a feeding port and a discharge port, the spool hole being in communication with a drain port, the feeding port being configured to receive a hydraulic fluid fed thereto, and the discharge port being configured to discharge the hydraulic fluid; and a spool movably provided in the spool hole, wherein the spool has: a connection recess defined in an outer surface of the spool, the connection recess being configured to establish communication between the feeding port and the discharge port; and a liaison channel establishing communication between the connection recess and the drain port, and wherein, within the liaison channel, a flow channel is formed between the spool hole and the outer surface of the spool, the flow channel serves as a filter to stop foreign matter from entering into the drain port, wherein a radial width of the flow channel is sized to inhibit passage of foreign matter of a desired size, wherein the flow channel constitutes a given part of a gap formed between the spool hole and the outer surface of the spool, and characterized in that the flow channel has a greater radial width than a remaining part of the gap formed between the spool hole and the outer surface of the spool since a reduced diameter portion is formed directly in the spool and the flow channel is formed between an outer surface of the reduced diameter portion and an inner surface of the spool hole, or since an increased diameter portion is formed directly in the spool hole and the flow channel is formed between an inner surface of the increased diameter portion and the outer surface of the spool. a connection recess defined in an outer surface of the spool, the connection recess being configured to establish communication between the feeding port and the discharge port; and a liaison channel establishing communication between the connection recess and the drain port, and wherein, within the liaison channel, a flow channel is formed between the spool hole and the outer surface of the spool, the flow channel serves as a filter to stop foreign matter from entering into the drain port, wherein a radial width of the flow channel is sized to inhibit passage of foreign matter of a desired size, wherein the flow channel constitutes a given part of a gap formed between the spool hole and the outer surface of the spool, and characterized in that the flow channel has a greater radial width than a remaining part of the gap formed between the spool hole and the outer surface of the spool since a reduced diameter portion is formed directly in the spool and the flow channel is formed between an outer surface of the reduced diameter portion and an inner surface of the spool hole, or since an increased diameter portion is formed directly in the spool hole and the flow channel is formed between an inner surface of the increased diameter portion and the outer surface of the spool.