A direct ion imaging system with single ion detection and high-precision imaging modes has been developed. This system is composed of a movable microchannel plate unit and a stacked CMOS-type active pixel sensor (SCAPS). Capabilities of single ion detection were evaluated by ion irradiations using secondary ion mass spectrometry. The experiment shows that this system accurately detected single incident ions. Copyright © 2006 John Wiley & Sons, Ltd.