PROBLEM TO BE SOLVED: To provide a surface modification method of a nickel nanoparticle for improving a heat shrinkability of a nickel nanoparticle having a particle diameter of, for example, 150 nm or less upon sintering.SOLUTION: A surface modification method of a nickel nanoparticle comprises a process for forming a coated film of nickel oxide by treating a nickel nanoparticle of (1) having an average particle diameter within a range of 20 nm to 150 nm, (2) having a weight loss rate from room temperature to 500°C in nitrogen atmosphere of 0.5 to 5%, and (3) having a coated film of hydroxide while detecting no crystalline nickel hydroxide in an X-ray diffraction, with plasma of an oxygen containing gas generated by glow discharge. The concentration of the oxygen containing gas in the glow discharge is preferably within a range of 0.01 volume% to 10 volume%.
