in the basic configuration to the following detailed exemplary embodiments first in the structure for improving limit load of a cam and a cam follower according to the present disclosure the grooves 11 a formed in a lattice pattern have depths d widths w and gaps i as shown in fig5 the present disclosure has been made in effort to improve limit load on the friction surface between the cam not shown and the cam follower 10 using the grooves 11 a formed in a lattice pattern for example it is preferable that the widths of the grooves 11 a are 0 05 to 0 25 mm the reason is because an oily layer pressure generation effect increases and the lubrication improvement effect is excellent when the widths of the grooves 11 a are 0 05 to 0 25 mm for example it is preferable that the gaps of the grooves 11 a are 0 5 to 2 0 mm the reason is because an oily layer pressure generation effect increases and the lubrication improvement effect is excellent when the gaps of the grooves 11 a are 0 5 to 2 0 mm for example the contact surface 11 may be composed of a plurality of grooves 11 a having various shapes such as lattice pattern for example it is preferable that load per cam width is 30 kgf mm or less under an operating condition in which viscosity of the liquid lubricant is 0 02 pa u00b7 s or less the reason i.