Provided is a flow rate control valve with which torque when rotating a valve body inside a housing can be reduced. The flow rate control valve is provided with a seal member for limiting leakage of fluid from a main communication hole or a main opening into a gap. A valve body, which is rotated by a driving mechanism, brings a first auxiliary communication hole into communication with a first auxiliary opening regardless of the rotation position of the valve body and changes, according to the rotation position of the valve body, the state of communication between the main communication hole and the main opening and the state of communication between a second auxiliary communication hole and a second auxiliary opening. A pressure loss is applied by the gap, which is formed between the inner circumferential surface of a valve body-housing section and the outer circumferential surface of the circumferential wall of the valve body, on fluid leaking out to the second auxiliary communication hole through the gap. The flow rate control valve is configured so that when the main communication hole is in communication with the main opening and the second auxiliary communication hole is notin communication with the second auxiliary opening, the amount of fluid leaking out to the second auxiliary communication hole is set according to the amount permitted in the device that is connectedto the main communication hole.

本发明提供可以降低驱动壳体内的阀芯旋转时的转矩的流量控制阀。流量控制阀具备抑制流体从主连通孔或主开口部向间隙部泄漏的密封部件，被驱动机构驱动而旋转的阀芯不论阀芯的旋转位置如何都使第一副连通孔和第一副开口部连通，并且，根据阀芯的旋转位置使主连通孔和主开口部的连通状态、以及第二副连通孔和第二副开口部的连通状态变化。借助在阀芯收容部的内周面和阀芯周壁的外周面之间形成的间隙部，给经由该间隙部向第二副连通孔漏出的流体带来压力损失，在主连通孔和主开口部连通并且第二副连通孔和第二副开口部未连通的状态下，根据在与主连通孔连接的装置中被容许的量来设定流体向第二副连通孔漏出的量。