Confocal X‐ray fluorescence (XRF) spectrometry can be used to perform three‐dimensional elemental analysis, which is impossible using general micro XRF spectrometry without any collimating optics in the detection channel. In this study, we designed, for the first time, a new confocal line XRF (C‐L‐XRF) system that can obtain elemental information of a larger area and higher intensity in XRF analysis than conventional confocal point XRF (C‐P‐XRF) analysis. We evaluate the basic performance of C‐L‐XRF, such as XRF intensity and horizontal and depth spatial resolutions. We identified that the spatial resolution of C‐L‐XRF in the horizontal and depth directions is approximately 2.9 and 2.6 times those of conventional C‐P‐XRF. However, it is possible to obtain an XRF intensity that is approximately 33 times higher than C‐P‐XRF intensity. C‐L‐XRF is expected to be effective for analyzing wide‐area samples such as layered samples. [ABSTRACT FROM AUTHOR]