Some possible collocation strategies of sensor and actuator pairs for the application to active vibration control systems are analyzed, compared and discussed in this paper. This is becausea well-designed sensor - actuator collocation configuration can provide a simpler control algorithm with excellent performance and stability, especially when velocity feedback is adopted. As an ideal point collocation pair of a sensor and actuator shows high possibility in actual vibration control problems, the advantage of a collocated accelerometer - shaker pair is proven experimentally and discussed first. Then as a similar approach, a collocated piezosensor - piezoactuator pair is analyzed in depth with the in-plane motion coupling. Finally, two configurations of a practically collocated configuration with an accelerometer - piezoactuator pair and a non-overlapped collocated pair of a bimorph piezosensor - two bimorph piezoactuators are described in detail in terms of performance and stability with experimental results. Those two configurations are expected for the applications to more practical active control of vibration systems with the velocity feedback control scheme.