A microscope focusing mechanism includes a fixing part attached to a microscope main body, a fixing-side guide member attached to the fixing part, a plate-shaped base part that supports at least one of a stage for placing a specimen and a revolver to which multiple objective lenses are detachably attached, a moving-side guide member that is fixed to the base part, that is connected to the fixing-side guide member, and that is movable in a direction of an optical axis of one of the objective lenses, and a plate member that is arranged on a side of the base part opposite to a side where the moving-side guide member is arranged. A linear expansion coefficient of a material of each of the moving-side guide member and the plate member differs from a linear expansion coefficient of a material of the base part.