A method of producing (1) metal particles or (2) metal fine-particles, which contains: jetting out two solutions of (1) a metal salt solution and a reducing agent solution, or (2) a metal ion-containing solution and a hydroxide ion-containing solution, from respective nozzles to a mixing chamber, to give a mixed reaction solution; and discharging the mixed reaction solution from a discharging port having a diameter smaller than a diameter of the mixing chamber, wherein one of the two solutions is made into straightly-going flow, which is jetted from a nozzle having a diameter smaller than the diameter of the mixing chamber to the mixing chamber, and the other solution is jetted out, as flow substantially orthogonal to the straightly-going flow, to a position before a position where eddy viscosity generated by the straightly-going flow would be maximum.