A system was developed to automatize the elution process in solid-phase extraction of trace element. The system consisted of a peristaltic pump and two switching valves. The switching valves were controlled by Arduino Uno, which is a microcontroller board. In the extraction process, a chelating resin, Presep PolyChelate, which is a macroporous methacrylate resin immobilizing partly carboxymethylated polyethyleneimine as a functional group, was used. The chelating resin was packed into a luer-type cartridge; a sample solution containing Ni as a trace element was passed through the cartridge to extract Ni with the resin. The cartridge was put on the system, and then the extracted Ni was eluted automatically. In this study, the conditions for the elution of Ni were optimized.