Intensive investigations on metal nanoparticles suspended in solutions have been undertaken because of their unique size-dependent electronic, optical, magnetic and chemical properties. Silver and gold nanoparticles have been extensively studied as they show a strong absorption band in the visible region, which is due to the excitation of the surface plasmon resonance. Recently, attention has been focused on Cu nanoparticles due to their catalytic and electrocatalytic properties. Since copper nanoparticles are highly unstable for oxidation compared with Au and Ag, Cu nanoparticles precipitate immediately after the exposure into the air, and an inert gas environment is required to stabilize copper colloids solution. A number of different methods have been developed to prepare metal nanoparticles, such as chemical, photochemical, electrochemical, and radiolytic reduction. In order to acquire stable colloidal suspensions, the stabilizing agents such as polymers and surfactants are usually employed in preparation. However, for the optimal application, a pure metal colloid solution is preferred because the additives can interfere with the interaction between reactants and metal surface, and eliminate or reduce the catalytic effect. The ablation technique has been applied to form metal colloidal solution in various solvents under protective-agentfree conditions by irradiating metal plate. According to Neddersen et al., since copper metal is highly reactive, it is difficult to prepare stable colloids in the water and a solution with olive-green color was obtained by irradiating copper plate in an aerobic environment, indicating oxidation from copper to copper oxide. However, Yeh et al. reported a generation of stable Cu colloids from CuO powder in 2propanol by laser ablation under the aerobic and protectiveagent-free conditions. Although they did not provide a detailed explanation, they demonstrated the reducing power of 2-propanol from the production of acetone during the ablation of CuO powder. In this study, we demonstrate a method to generate stable Cu nanoparticles from Cu powder dispersed in 2-propanol by the laser ablation technique under aerobic condition. In case of using the metal plate as the ablation target, it is difficult to adjust the focus of laser light on the metal surface immersed in solvent, and the turbulence of fluid which is generated by plume expansion can protect next laser pulse to arrive at metal surface, and the metal plate has to be continuously rotated to prevent the irradiation of laser light on the same position of the metal plate. Furthermore, if the concentration of nanoparticles increases as the ablation proceed, the laser light become more difficult to arrive at the metal surface by self absorption of nanoparticles. The use of Cu powder dispersed in solution can be simple alternatives to maintain the homogeneity of the sample during the ablation.