A method of forming a bonded product using metal nanoparticles is provided. More specifically, provided is a paste containing a flux component that can form a metal phase even in an inert atmosphere. The use of this paste allows a bonding material that can give a practically acceptable bonding strength to be provided in an inert atmosphere such as a nitrogen atmosphere at low temperatures without performing conventionally used pressurization. The paste is a bonding material configured to include: silver nanoparticles having an average primary particle diameter of 1 to 200 nm and coated with an organic material having 8 or less carbon atoms; a flux component having at least two carboxyl groups; and a dispersion medium. The use of this bonding material allows materials to be bonded even at a temperature of 300°C or lower.