PURPOSE: To obtain a high reliability even in repeated measuring operation by forming a flat surface not vertical to the axis on one end surface outer circumferential surface of a cuvette so as to be matched to an electrode corresponding surface.

CONSTITUTION: Both end parts of a cylindrical cuvette 1 having a sample injecting hole 2 are fitted into the inside of electrode blocks 3, 3' mounted on electrode holders 4, 4' having inert gas injecting small holes 5, 5'. A sample solution put from the injecting hole 2 is heated in the cuvette 1 by a power source device 6, a specified wavelength light is emitted to the cuvette space part containing the atomized metal component from a light source device 7, and the transmitted light is measured by a light measuring device 8. During this, an inert gas is sent thereto at a fixed speed through the small holes 5, 5', and the absorbed light quantity or metal component quantity is calculated from the difference between the incident light quantity and the transmitted light quantity. Thus, the positioning of the cuvette at the time of installation to an electrode and the assembling of an atomizing furnace are facilitated, and a stabilized high measurement precision can be obtained in repeated measurement.