The present invention provides a controlled release solid preparation superior in the stability of an active ingredient, which can exhibit pharmacological effects steadily and rapidly after administration, and shows a sustained pharmacological effect for a prolonged period of time: a controlled release solid preparation containing (1) an antacid, (2) an immediate-release part containing a compound unstable to acid and a basic substance, and (3) a sustained-release part containing a compound unstable to acid and a pH-independent material in combination.