A hose clamp which is formed into a ring-like shape by bending a strip-like plate material so as to cause it to cross itself in a peripheral plane to thereby form a tightening portion and which can tighten a connection portion between a hose and a mating member thereof by means of this tightening portion, wherein a first end portion arranged at one longitudinal end side and having a first pinching operation surface at an end portion thereof, the first end portion being provided with a through-hole which is open on the first end portion side and located nearer to the center in the longitudinal direction than the first pinching operation surface; and a second end portion arranged at the other longitudinal end side and having at an end portion thereof a second pinching operation surface (15; 60; 70; 80; 90), the second end portion being provided with a small-width portion and located nearer to the center in the longitudinal direction than the second pinching operation surface (15; 60; 70; 80; 90) and which is configured to enter the through-hole, wherein at least one of the first pinching operation surface and the second pinching operation surface (15; 60; 70; 80; 90) is formed by: a proximal region not including a portion interfering with the first end portion or the second end portion constituting a mating side when the plate material is bent into a ring-like shape along an axis constituting a center axis extending along the longitudinal direction thereof, an expansion region provided at a side edge portion in a widthwise direction of the proximal region and including a portion interfering with the first end portion when the plate material is bent along the center axis into the ring-like shape; and a folding edge provided between the proximal region and the expanding region configured to allow folding of the expansion region, the expansion region being configured to be foldable at the folding edge in order to set an outer width dimension of the second pinching operation surface (15; 60; 70; 80; 90) to be equal or smaller than an opening width of the trough-hole, so that the second pinching operation surface (15; 60; 70; 80; 90) is configured to be insertable into the trough-hole when the plate material is bend along the center axis; and the expansion region being configured to be unfoldable at the folding edge in order to set the outer width dimension of the second pinching operation surface (15; 60; 70; 80; 90) to be larger than the opening width of the trough-hole of the first end portion, characterized in that said second pinching operation surface (15; 60; 70; 80; 90) of said second end portion arranged at the other longitudinal end side is formed in a width dimension larger than the maximum opening width of the through hole. a proximal region not including a portion interfering with the first end portion or the second end portion constituting a mating side when the plate material is bent into a ring-like shape along an axis constituting a center axis extending along the longitudinal direction thereof, an expansion region provided at a side edge portion in a widthwise direction of the proximal region and including a portion interfering with the first end portion when the plate material is bent along the center axis into the ring-like shape; and a folding edge provided between the proximal region and the expanding region configured to allow folding of the expansion region, the expansion region being configured to be foldable at the folding edge in order to set an outer width dimension of the second pinching operation surface (15; 60; 70; 80; 90) to be equal or smaller than an opening width of the trough-hole, so that the second pinching operation surface (15; 60; 70; 80; 90) is configured to be insertable into the trough-hole when the plate material is bend along the center axis; and the expansion region being configured to be unfoldable at the folding edge in order to set the outer width dimension of the second pinching operation surface (15; 60; 70; 80; 90) to be larger than the opening width of the trough-hole of the first end portion, characterized in that said second pinching operation surface (15; 60; 70; 80; 90) of said second end portion arranged at the other longitudinal end side is formed in a width dimension larger than the maximum opening width of the through hole.