A control valve (100, 200) including a spool that is incorporated into a valve main body to be free to slide, and a first pilot chamber and a second pilot chamber disposed to face respective ends of the spool, wherein the spool is moved by an action of a pilot pressure led into one of the first pilot chamber and the second pilot chamber, the control valve (100, 200) comprising: a signal pressure passage (18, 19, 24) that is formed in the valve main body and transmits the pilot pressure in the first pilot chamber or the second pilot chamber as a signal pressure for another device; a first connecting groove (20, 22) that is formed in the spool and connects the first pilot chamber to the signal pressure passage (18, 24) when the spool is in a neutral position; and a second connecting groove (21, 23) that is formed in the spool and connects the second pilot chamber to the signal pressure passage (19, 24) when the spool is in the neutral position, characterized in that, when the pilot pressure is led into the first pilot chamber such that the spool moves, the first connecting groove (20, 22) remains connected to the signal pressure passage (18, 24) such that the first pilot chamber and the signal pressure passage (18, 24) communicate with each other, while the second connecting groove (21, 23) separates from the signal pressure passage (19, 24) such that communication between the second pilot chamber and the signal pressure passage (19, 24) is blocked, and when the pilot pressure is led into the second pilot chamber such that the spool moves, the second connecting groove (21, 23) remains connected to the signal pressure passage (19, 24) such that the second pilot chamber and the signal pressure passage (19, 24) communicate with each other, while the first connecting groove (20, 22) separates from the signal pressure passage (18, 24) such that communication between the first pilot chamber and the signal pressure passage (18, 24) is blocked. a signal pressure passage (18, 19, 24) that is formed in the valve main body and transmits the pilot pressure in the first pilot chamber or the second pilot chamber as a signal pressure for another device; a first connecting groove (20, 22) that is formed in the spool and connects the first pilot chamber to the signal pressure passage (18, 24) when the spool is in a neutral position; and a second connecting groove (21, 23) that is formed in the spool and connects the second pilot chamber to the signal pressure passage (19, 24) when the spool is in the neutral position, characterized in that, when the pilot pressure is led into the first pilot chamber such that the spool moves, the first connecting groove (20, 22) remains connected to the signal pressure passage (18, 24) such that the first pilot chamber and the signal pressure passage (18, 24) communicate with each other, while the second connecting groove (21, 23) separates from the signal pressure passage (19, 24) such that communication between the second pilot chamber and the signal pressure passage (19, 24) is blocked, and when the pilot pressure is led into the second pilot chamber such that the spool moves, the second connecting groove (21, 23) remains connected to the signal pressure passage (19, 24) such that the second pilot chamber and the signal pressure passage (19, 24) communicate with each other, while the first connecting groove (20, 22) separates from the signal pressure passage (18, 24) such that communication between the first pilot chamber and the signal pressure passage (18, 24) is blocked.