ONBOARD BATTERY CASE STRUCTURE

Provided is an in-vehicle battery case structure that is excellent in protection effect from an external impact and is capable of suppressing deterioration of resource values at the time of recycling. The in-vehicle battery case structure includes: a battery case configured to be mounted in a vehicle; and a plurality of strength members fastened to the inner side of the battery case, the strength members are configured to hold a battery module, and each of the strength members is detachably fastened to the battery case and is configured by a plurality of components that are joined through joining without dissimilar materials.