An inkjet printer correction device and method. A correction device having a first circuit generating a first processing signal composed of a first and second pulse signal according to a first and second phase signal produced by an encoder, a second circuit generating a second processing signal based on the position change variation of either the first or second phase signal, a third circuit generating a third processing signal based on the position change variation of either the first or second phase signal, a selector selecting one of the first, second, or third circuits according to the first processing signal. The present invention provides one of the first, second, or third processing signals to control the speed and position of motor of the inkjet printer.