A drug solution injection controller 10 includes a sub-reservoir 24 connected via a sub-line 26 to a main line 14 for performing continuous administration of a drug solution such that rapid administration of the drug solution from the sub-reservoir 24 by self-operation is enabled, and comprises: a priming flow path 46 configured to perform priming on at least one of the main line 14 and the sub-line 26; a closing mechanism 48 configured to close the priming flow path 46; and a connector holding part 84 holding a terminal connector 18 connected to the main line 14. Holding of the terminal connector 18 by the connector holding part 84 is allowed to be released due to operation of an operation switch 50 configured to activate the closing mechanism 48.