A robot controller capable of minimizing an increase in the tact time during work, reducing changes in joint axes of the robot, thereby providing the structure with long mechanical life. The robot controller i) stores a plurality of movement data formed of amount and time for movement; ii) checks whether a movement of a robot has acceleration exceeding a predetermined level by calculation on the basis of the stored movement data; iii) increases the time for movement of the corresponding movement data, the preceding and following data to the movement data, if the calculation indicates over-acceleration; and iv) controls the robot according to the time-increased movement data.