An analytical technique of rare-earth elements (REE) in rock samples using a high-performance ion chromatography (HPIC) is described. The REE in rock samples were separated from other elements using a conventional ion-exchange column, and then measured by the HPIC. α-hydroxyisobutyric acid and Arsenazo III were used for eluants and a post-column reagent for the HPIC, respectively. The use of a high-resolution HPIC column enabled to analyze all fourteen REE without any interference from Y and other transition metals. The REE concentrations determined for twelve Geological Survey of Japan rock reference samples, having varied major element compositions, showed good agreement with the recommended values and the values recently obtained by inductively coupled plasma-mass spectrometry (ICP-MS). This HPIC technique provides an inexpensive means to obtain high-quality data of all fourteen REE in rock samples as small as <50 mg, and potential for wide geochemical applications as an alternative to ICP-MS.