Disc drive device

A disk driving device is provided, which is provided with a mechanism preventing falling off of a rotor part. The mechanism preventing falling off is formed by that: after being inserted into a stator part, the rotor part is plastically deformed towards the inner side of the diameter direction with an unciform part formed via integral cut out of a rotary table part, thereby being jointed with the joint part of a metal shell in the axis direction. Thus, the unciform part as one part of the mechanism preventing falling off is integrally formed on the rotary table part, which can reduce the quantity of the parts and improve assembling ability.