To provide a coordinate input device which allows a device side for mounting a mounting board to be miniaturized, and which is superior in operationality since an operation shaft can be easily operated even with a small operation load.

The mounting board 1 of a coordinate input device has three fixed parts 1b which can be fixed to an external fixing member (not shown in a figure) and three mounting parts 1c for mounting a sensor substrate 3 on the lower face side. The mounting board 1 on which the sensor substrate 3 is mounted is mounted and fixed on the lower face side of the fixing member (not shown in the figure) so that an operation shaft 2 can be erected through the fixing member. Thus, it is possible to effectively utilize the fixing member in the periphery of the operation shaft, and to miniaturize an external fixing member, for example, the chassis of a keyboard device.