The IM-11-2 is a pneumatically operated microinjector that allows suction and injection of a microsample with high precision and operability comparable to oil hydraulic injectors. Equipped with a coarse-fine coaxial control knob, the microinjector enables both coarse and fine movement operation. As compared to the existing pneumatic injectors such as the IM-9C, the IM-11-2 has substantially improved on the amount of pressure change per knob rotation, thereby enabling finer and more powerful control.