Abstract: A seat belt buckle system which is easy to engage and disengage includes a plunger section with a cylindrical plunger pin, mounted to a base, which is formed to fit closely within the bore of a receptacle forming part of a receptacle section. The receptacle section also includes a base to which a flexible seat belt can be connected. The buckle is engaged by inserting the plunger pin into a flared entrance end of the receptacle, which guides the leading end of the plunger pin into the bore of the receptacle. The plunger pin is held in place by the engagement of the pin to the internal walls of the receptacle and by engagement of a spring loaded detent ball against the side wall of the plunger pin, the end wall of the plunger pin or an indentation formed in the plunger pin. The bases of the receptacle section and plunger section can be modified to mate with the standard seat belt plunger plate and receiver of conventional seat belt systems to allow retrofitting of such systems.