To provide a fuel injection valve control device and system capable of accurately estimating a piezo displacement or load.

The fuel injection valve control device and the fuel injection valve control system are applied to a piezo injection with a piezo element. The device includes virtual voltage estimating means B40, B41, B42 for estimating a possible voltage of the piezo element as a virtual voltage V0 if the piezo element is in an unladen state not receiving external force from a back pressure control valve during charging and discharging to the piezo element, an actual voltage measuring means for measuring an actual voltage V of the piezo element during the charging and discharging, and a calculating means for calculating the displacement Z or the load F of the piezo element on the basis of a voltage difference V of subtracting the virtual voltage V0 from the actual voltage V.