To provide a desk leaf base that facilitates replacement of a leaf group.

The desk leaf base includes a base and a binder. A trapezoidal cylindrical body having a trapezoidal shape in a side planar view is configured such that both sides are closed from the bottom surface to a certain height and parts above the certain height are opened. The base is composed of the trapezoidal cylindrical body. The base is formed by cutting off the range from the certain height to another height, higher than the certain height and lower than the top surface, of the inclined front-face wall over an area from one side to the other side. The binder is mounted along the elongated top surface of the base and includes an elongated body and a plurality of rings. The body is mounted along the top surface of the base at almost the same width as that of the top surface. The plurality of rings are mounted to the body to be openable/closable. Each of the plurality of rings includes a linear part that protrudes from the body and extends upwardly and inclinedly above the front-face side and the rear-face side.