A semiconductor device includes a plurality of core chips and an interface chip stacked together. Each of the core chips and the interface chip includes plural through silicon vias that penetrate a semiconductor substrate and a bidirectional buffer circuit that drives the through silicon vias. The interface chip also includes a logic-level holding circuit that holds a logic level of the through silicon vias. The bidirectional buffer circuit includes an input buffer and an output buffer. The driving capability of a first inverter of the logic-level holding circuit is smaller than the driving capability of the output buffer of the bidirectional buffer circuit.