Background Studies have been conducted on slave-specific master devices with a similar kinematic structure to the slave to enhance intuitiveness. However, for the four-degrees of freedom (DOFs) slave of a flexible endoscopic surgery robot, only four DOFs in the master device causes low ergonomic performance. Methods To enhance ergonomic performance, a second yaw joint was added as a redundant joint after considering the range of wrist motion and the workspace shape. Three experiments were performed to compare the intuitiveness and ergonomic performance of the proposed device with four-DOFs slave-specific and six-DOFs general-purpose master devices. Results Significant differences were observed in terms of intuitiveness performance between the slave-specific and the general-purposed master device. On the other hand, there was no significant difference in ergonomic performance between the master devices with redundant joint. Conclusions Compared with a general-purpose master device, the proposed one exhibited noticeably improved intuitiveness performance and comparable ergonomic performance.