In a medicament dispensing device (1), when a medicament preparation-containing syringe (11) is replaced, a microprocessor (23) detects the time at which the replacement is performed as the time of the start of use of the preparation, and counts the elapsed time after the use of the preparation has started. Then, the microprocessor (23) notifies the result of the counting by a LCD (10), etc. to the user. Also, the microprocessor (23) detects that a syringe needle for dispensing the preparation has been mounted, and after detecting the mounting of the syringe needle, the microprocessor (23) counts the elapsed time after the start of use of the preparation. When an effective use period has expired, the microprocessor (23) issues a message in a step S17 that the effective period of a medicament has expired.