A cycloidal speed reducer comprising: a casing; an input shaft having one end arranged in said casing; a disk-shaped eccentric member (25a, 25b) eccentric with respect to an axis of said input shaft and coupled to the one end of the input shaft; a revolution member (26a, 26b) supported by said eccentric member (25a,25b), to make a revolution motion around said axis together with a rotation of said input shaft; a rolling bearing arranged between an inner circumference of said revolution member (26a, 26b) and an outer circumference of said eccentric member(25a,25b); an outer circumference engagement member supported by said casing and engaging with an outer circumference part of said revolution member (26a, 26b) to cause the revolution member to make a rotation motion; and an output shaft engaging with said revolution member (26a, 26b) to extract the rotation motion, wherein said rolling bearing has a rolling body and an inner ring member mounted on the outer circumference of said eccentric member (25a,25b), characterized in that said rolling bearing has a lubricant oil hole penetrating from an inner diameter surface of the inner ring member to an outer circumference track surface thereof to supply a lubricant oil to the outer circumference track surface of the inner ring member being in rolling contact with said rolling body, and said lubricant oil hole is arranged in a non-load range in which a bearing load is not applied from said output shaft and said outer circumference engagement member to said revolution member (26a, 26b), in the outer circumference track surface of said rolling bearing wherein said lubricant oil hole is arranged in a range from 90 degrees to 270 degrees circumferentially away from a portion receiving a highest bearing load to be shared, in said outer circumference track surface and wherein a bearing internal gap of said rolling bearing is a positive gap, and wherein the input shaft has an axis oil path, and the eccentric member (25a, 25b) has a lubricant oil path (58a, 58b) extending from the axis oil path toward the radial outer side in the eccentric member (25a, 25b), and a radial outer side end of the lubricant oil path (58a, 58b) is connected to the lubricant oil hole through an annular groove which circumferentially extends between the eccentric member (25a, 25b) and the inner ring member. a casing; an input shaft having one end arranged in said casing; a disk-shaped eccentric member (25a, 25b) eccentric with respect to an axis of said input shaft and coupled to the one end of the input shaft; a revolution member (26a, 26b) supported by said eccentric member (25a,25b), to make a revolution motion around said axis together with a rotation of said input shaft; a rolling bearing arranged between an inner circumference of said revolution member (26a, 26b) and an outer circumference of said eccentric member(25a,25b); an outer circumference engagement member supported by said casing and engaging with an outer circumference part of said revolution member (26a, 26b) to cause the revolution member to make a rotation motion; and an output shaft engaging with said revolution member (26a, 26b) to extract the rotation motion, wherein said rolling bearing has a rolling body and an inner ring member mounted on the outer circumference of said eccentric member (25a,25b), characterized in that said rolling bearing has a lubricant oil hole penetrating from an inner diameter surface of the inner ring member to an outer circumference track surface thereof to supply a lubricant oil to the outer circumference track surface of the inner ring member being in rolling contact with said rolling body, and said lubricant oil hole is arranged in a non-load range in which a bearing load is not applied from said output shaft and said outer circumference engagement member to said revolution member (26a, 26b), in the outer circumference track surface of said rolling bearing wherein said lubricant oil hole is arranged in a range from 90 degrees to 270 degrees circumferentially away from a portion receiving a highest bearing load to be shared, in said outer circumference track surface and wherein a bearing internal gap of said rolling bearing is a positive gap, and wherein the input shaft has an axis oil path, and the eccentric member (25a, 25b) has a lubricant oil path (58a, 58b) extending from the axis oil path toward the radial outer side in the eccentric member (25a, 25b), and a radial outer side end of the lubricant oil path (58a, 58b) is connected to the lubricant oil hole through an annular groove which circumferentially extends between the eccentric member (25a, 25b) and the inner ring member.