To provide a flow control device and a flow control system capable of reducing a load on an actuator driving a valve.

A flow control device 18 includes: a valve body 20 in which a first flow channel 21, a valve chamber 22, a second flow channel 23, and a valve seat portion 24 are provided; a diaphragm 42 that lays out an inside and an outside of the valve chamber 22; and a valve body 41 that is connected to the diaphragm 42 and is provided opposed to the valve seat portion 24. The flow control device 18 includes: a piston rod 60 that is connected to the valve body 41; a stepping motor 90 that reciprocally drives the piston rod 60 so as to change a distance between the valve seat portion 24 and the valve body 41; and a pressurizing/depressurizing unit 12 that exerts a static load in a reciprocal driving direction on the piston rod 60.