NOVELTY - A composition comprises a metal nanoparticle, where a secondary aggregation diameter (median diameter) is less than or equal to 2 mu m as determined by disk centrifugal-type particle size distribution measurement.    USE - As metal nanoparticle composition useful for forming metal thin film, metal wiring pattern, antenna for RFID and RFID inlet (claimed). Also useful in printed electronics such as printed CPUs, printed lighting devices, printed RFID tags, all-printed displays, sensors, printed wiring boards, organic solar cells, electronic books, and printed memories.    ADVANTAGE - The metal nanoparticle composition exhibits good adhesion to a substrate and forms a metal film or a conductive circuit at low temperatures in a short time. A high quality finished metal film excellent in a low temperature sintering property is obtained with good reproducibility by using the metal nanoparticles composition.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a method for manufacturing the composition of the metal nanoparticle, where the synthesization of the metal nanoparticle is performed while stirring under a condition with nd(2/3) being not greater than 160 in a step for synthesizing the metal nanoparticle, where n (rotation per minute) is the number of rotation of a stirrer and d (m) is a diameter of a stirring blade;    (2) a metal thin film formed by coating the composition of the metal nanoparticle, and then firing the coated dispersion in air at less than or equal to 140 degrees C for less than 90 seconds;    (3) a metal wiring pattern, formed by forming a thin line by the composition of the metal nanoparticle, and then firing the thin line in air at less than or equal to 140 degrees C for less than 90 seconds for metallization;    (4) an antenna for radio frequency identification (RFID), formed by forming a thin line by the composition of the metal nanoparticle, then firing the thin line in air at less than or equal to 140 degrees C for less than 90 seconds for metallization to form a metal thin line, and forming an antenna portion for RFID using the metal thin line; and    (5) an RFID inlet using the antenna.