A semiconductor device includes a substrate, a plurality of lower electrodes disposed on the substrate and are repeatedly arranged in a first direction and in a second direction that crosses the first direction, and a first electrode support contacting a sidewall of at least one of the lower electrodes. The first electrode support includes a first support region including a first opening and a second support region disposed at a border of the first support region. An outer sidewall of the first electrode support includes a first sidewall extending in the first direction, a second sidewall extending in the second direction, and a connecting sidewall connecting the first and second sidewalls. The second support region includes the connecting sidewall. In a first portion of the second support region, a width of the first portion of the second support region decreases in a direction away from the first support region.