To provide a touch panel mounting structure capable of securing waterproofness, even when a touch panel itself is not provided with waterproofness and capable of providing a superior operation feeling.

The touch panel mounting structure includes: a casing 5 on which a recess 15 is formed; a liquid crystal panel/touch panel assembly configured by a liquid crystal panel 17 and a touch panel 21 formed on the liquid crystal panel 17 so as to cover an image display surface 19 of the liquid crystal panel 17 and installed in the recess 15 of the casing 5; a protection sheet closing an opening of the recess 15 in which the liquid crystal panel/touch panel assembly is installed; an biasing unit for biasing the liquid crystal panel/touch panel assembly installed in the recess 15 of the casing 15 in a direction toward the opening side of the recess 15; and a ratcher for locking the liquid crystal panel/touch panel assembly biased by the biasing unit against the biasing by the biasing unit.