In a probe unit having a measuring probe, a signal processing circuit includes: a signal synthesizing portion configured to process an output of a detection element to output a composite signal obtained by synthesizing displacement components of a contact part in three directions perpendicular to one another; and a signal outputting portion configured to output a digital touch signal to the outside of the probe unit when the composite signal satisfies a predetermined threshold condition. The signal outputting portion includes three comparing portions each configured to compare a threshold condition with the composite signal. When the measuring probe measures the object to be measured, the signal outputting portion outputs the digital touch signal corresponding to outputs of the first and second comparing portions. Thus, there can be provided a probe unit and a measuring system that can stably make measurements with high accuracy while keeping high noise resistance.