A case structure for a computer device is disposed in a cabinet. The case structure includes a case and a stop member. The case has a first slot on a sidewall of the case. The stop member includes a fixing section, a cantilever section, and a stop section. The fixing section is fixed on a side surface of the case. The cantilever section is formed by extending from the fixing section and may be deformed. The stop section is formed by extending from the cantilever section. At least one blocking piece is disposed on a side surface of the stop section. The blocking piece normally passes through the first slot and protrudes on an outer side surface of the case, so that the blocking piece is held against the cabinet. When the cantilever section is deformed, the blocking piece is merged into the first slot.