Motor imagery is a complex cognitive action that represents mentally the process of performing a movement (from preparation to the intention). In the current study, the effect of internal versus close- or far- external instruction of attention focusing during motor imagery on response time of four well-trained karate skills was evaluated. In a semi-experimental design, 43 skilled athletes (24 women, 19 men; mean age: 15.88 ± 4.50) executed the pre-test in front of a researcher-made device. Unexpected visual stimuli were presented randomly by the device, and response times of each skill were recorded by a software synced to the device. Then, each of the Karatekas participated in one of three training groups of imagining, namely, internal attention (7 women, 7 men), close-external attention (6 women, 5 men), far-external attention (6 women, 5 men) in 12 sessions, or in a control group (5 women, 2 men). After performing the post-test identical to pre-test, by carrying out a mixed-model analysis of covariance, the results revealed that there was no significant effect of gender, and only close-external imagery resulted in promoting lower body techniques (p<0.05). However, such an effect did not observe for upper body techniques, and effect of keeping focus of attention on body extremities (internal attentional imagery) and on far outcome of movement (far-external attentional imagery) were not significant (p>0.05). The findings suggest, during mental rehearsal, the analogy of athlete’s external attentional strategy to actual task plays an important role on effectiveness of motor imagery.