An apparatus and method of controlling injection in an electric injection molding machine including a motor and a screw. The apparatus has an encoder detecting a current position of the screw and outputting the detected position as an encoding signal, a memory storing reference positions of the screw according to a drive of the motor by the passage of time, and a current controller checking an elapse of time that the screw moves from a previous position to a current position through receiving the encoding signal from the encoder, reading out a section of time corresponding to the checked elapse of time from the memory, and controlling a current value applied to the motor based on a difference between a reference position of the screw corresponding to the read-out section of time and a current position of the screw.