A snap fastener, of the type comprising a female part (2) including a spring (11, 11a, 11b) and a male part (4) including a stem (5) for engagement with the spring, wherein a chamber (10, 10a, 10b) is provided for housing the spring and including shoulders (12, 12a, 12b) on a buttoning side, the shoulders having a length (L1) longer than a length (L2) of shoulders (13, 13a, 13b) arranged on the opposite side. Thus, a differentiated effort buttoning and unbuttoning mechanism between the stem (5) and the spring (11) is achieved. With respect to prior snap fasteners, the inventive snap fastener provides the advantage of requiring very small buttoning efforts, much smaller than those necessary for unbuttoning the snap fastener, thereby facilitating the snap fastener closing operation while providing a tightness closure upon having buttoned the snap fastener male and female parts.

A buckle includes a male member and a female member. The male member is provided with an engagement section which protrudes from a body section. The female member includes a pressing elastic member which is provided with an engagement receiving section with which the engagement section engages; and a housing body in which a housing space for housing the pressing elastic member is housed. The housing body has an opening which connects to the housing space and into which the engagement section is inserted. The pressing elastic member is integrally provided with: a pair of pressing sections-which protrudes from the housing space of the housing body; elastic body sections which connect the pair of pressing sections together, elastically support the pressing sections, and enable the pressing sections to elastically move into the housing section; and the engagement receiving section which is supported by the elastic body sections.