A handrail device for guardrail, comprising a rail provided to form a handrail and a clamp provided for fixing the rail to an upright, wherein the rail extends along a longitudinal axis and has an outer peripheral face provided with a lower portion and an upper portion, and said rail has two median planes (PM1, PM2) which are, when the rail is in situation on the guardrail with the longitudinal axis to the horizontal: - a first median plane including the longitudinal axis and extending vertically, where the rail has a given height measured in the first median plane between a low point on the lower portion and a high point on the upper portion, and where the longitudinal axis is located approximately halfway between the high point and the low point; and - a second median plane above which the upper portion extends and below which the lower portion extends, where the second median plane includes the longitudinal axis and extends horizontally, orthogonal to the first median plane; and wherein the clamp comprises two articulated claws (51, 52) and is configurable between a tight configuration wherein the two claws (51, 52) grip a section of the rail, and a loose configuration allowing the introduction of the rail between the two claws (51, 52); said handrail device being characterized in that: - the rail has two longitudinal grooves provided in the lower portion of the outer peripheral face, these two longitudinal grooves extending parallel to the longitudinal axis and being arranged on either side of the first median plane, below the second median plane; and - the clamp, in the tight configuration, has its two claws (51, 52) engaged at least partially inside the two respective longitudinal grooves, these two claws (51, 52) not protruding above of the second median plane. wherein the rail extends along a longitudinal axis and has an outer peripheral face provided with a lower portion and an upper portion, and said rail has two median planes (PM1, PM2) which are, when the rail is in situation on the guardrail with the longitudinal axis to the horizontal: - a first median plane including the longitudinal axis and extending vertically, where the rail has a given height measured in the first median plane between a low point on the lower portion and a high point on the upper portion, and where the longitudinal axis is located approximately halfway between the high point and the low point; and - a second median plane above which the upper portion extends and below which the lower portion extends, where the second median plane includes the longitudinal axis and extends horizontally, orthogonal to the first median plane; - a first median plane including the longitudinal axis and extending vertically, where the rail has a given height measured in the first median plane between a low point on the lower portion and a high point on the upper portion, and where the longitudinal axis is located approximately halfway between the high point and the low point; and - a second median plane above which the upper portion extends and below which the lower portion extends, where the second median plane includes the longitudinal axis and extends horizontally, orthogonal to the first median plane; and wherein the clamp comprises two articulated claws (51, 52) and is configurable between a tight configuration wherein the two claws (51, 52) grip a section of the rail, and a loose configuration allowing the introduction of the rail between the two claws (51, 52); said handrail device being characterized in that: - the rail has two longitudinal grooves provided in the lower portion of the outer peripheral face, these two longitudinal grooves extending parallel to the longitudinal axis and being arranged on either side of the first median plane, below the second median plane; and - the clamp, in the tight configuration, has its two claws (51, 52) engaged at least partially inside the two respective longitudinal grooves, these two claws (51, 52) not protruding above of the second median plane. - the rail has two longitudinal grooves provided in the lower portion of the outer peripheral face, these two longitudinal grooves extending parallel to the longitudinal axis and being arranged on either side of the first median plane, below the second median plane; and - the clamp, in the tight configuration, has its two claws (51, 52) engaged at least partially inside the two respective longitudinal grooves, these two claws (51, 52) not protruding above of the second median plane.