A cross universal joint, comprising: a pair of yokes; and a joint spider that connects the yokes so as to be able to pivotally displace freely; each of the yokes made of metal and comprising: a base section for connecting and fastening to an end section of a rotating shaft; a pair of linking arm sections that extend in an axial direction from two locations on an edge of one end in the axial direction of the base section on opposite sides in a radial direction of the rotating shaft; and a pair of circular holes that are formed in tip end sections of the linking arm sections so as to be concentric with each other; and the joint spider made of a ferrous alloy and comprising four shaft sections that are provided so that center axes of adjacent shaft sections are orthogonal to each other, and tip end sections of these shaft sections are supported by way of bearings inside the circular holes that are provided in the yokes so as to be able to rotate freely; characterized in that reference lines, which are straight lines as seen from outside surfaces sides of the linking arm sections and that extend in an axial direction of the base sections, are displayed on the outside surfaces of the linking arm sections of at least one of the yokes, in at least the portions nearer to the base section than the circular holes, and the reference lines comprise protrusions that protrude outward of the base section from the outside surface of the linking arm sections and have a maximum height of about 0.5 mm or concave grooves that are depressed inward in the radial direction of the base section from the outside surface of the linking arm sections and have a maximum depth of about 0.5 mm. a pair of yokes; and a joint spider that connects the yokes so as to be able to pivotally displace freely; each of the yokes made of metal and comprising: a base section for connecting and fastening to an end section of a rotating shaft; a pair of linking arm sections that extend in an axial direction from two locations on an edge of one end in the axial direction of the base section on opposite sides in a radial direction of the rotating shaft; and a pair of circular holes that are formed in tip end sections of the linking arm sections so as to be concentric with each other; and the joint spider made of a ferrous alloy and comprising four shaft sections that are provided so that center axes of adjacent shaft sections are orthogonal to each other, and tip end sections of these shaft sections are supported by way of bearings inside the circular holes that are provided in the yokes so as to be able to rotate freely; characterized in that reference lines, which are straight lines as seen from outside surfaces sides of the linking arm sections and that extend in an axial direction of the base sections, are displayed on the outside surfaces of the linking arm sections of at least one of the yokes, in at least the portions nearer to the base section than the circular holes, and the reference lines comprise protrusions that protrude outward of the base section from the outside surface of the linking arm sections and have a maximum height of about 0.5 mm or concave grooves that are depressed inward in the radial direction of the base section from the outside surface of the linking arm sections and have a maximum depth of about 0.5 mm. a base section for connecting and fastening to an end section of a rotating shaft; a pair of linking arm sections that extend in an axial direction from two locations on an edge of one end in the axial direction of the base section on opposite sides in a radial direction of the rotating shaft; and a pair of circular holes that are formed in tip end sections of the linking arm sections so as to be concentric with each other; and the joint spider made of a ferrous alloy and comprising four shaft sections that are provided so that center axes of adjacent shaft sections are orthogonal to each other, and tip end sections of these shaft sections are supported by way of bearings inside the circular holes that are provided in the yokes so as to be able to rotate freely; characterized in that reference lines, which are straight lines as seen from outside surfaces sides of the linking arm sections and that extend in an axial direction of the base sections, are displayed on the outside surfaces of the linking arm sections of at least one of the yokes, in at least the portions nearer to the base section than the circular holes, and the reference lines comprise protrusions that protrude outward of the base section from the outside surface of the linking arm sections and have a maximum height of about 0.5 mm or concave grooves that are depressed inward in the radial direction of the base section from the outside surface of the linking arm sections and have a maximum depth of about 0.5 mm.