We validated the effectiveness of a coaxial needle insertion assistant under the condition that the needles were laterally deformed. The coaxial needle insertion assistant separates the cutting force at the needle tip from shear friction on the needle shaft, and haptically display it to a user in order to assists her/his perception during epidural puncture. An outer needle covers the side of an inner needle, preventing the shear friction from acting on the inner needle. However when the needles are laterally deformed and make contact to each other, it is concerned that the effect of the separation is degraded. In this paper, the users punctured an artificial tissue with variable insertion angles, so that the needle is intentionally laterally deformed. The overshoot and user confidence in detecting puncture was examined.