Chemical liquid injector 100 includes two piston driving mechanisms 130 each moving a piston of a syringe forward, main injection condition determining section 171 determining injection conditions for a chemical liquid in main injection, test injection condition determining section 172 determining injection conditions for the chemical liquid in test injection performed prior to the main injection to inject a smaller injection amount of the chemical liquid than that in the main injection, and control section 161 creating an injection protocol in accordance with the injection conditions determined by test injection condition determining section 171 and main injection condition determining section 172 such that the chemical liquid is injected in a series of operations in which the test injection is performed, then a preset injection suspension time is present, and subsequently the main injection is performed, and further controlling operation of piston driving mechanisms 130 in accordance with the injection protocol.
