PURPOSE: To realize a reasonable and economic conduction coupling device and a shaft member used in the device, by which any disadvantage in a conduction coupling means including a spline or the like can be effectively avoided.

CONSTITUTION: A conduction coupling device is formed by male-female interfit of a male-like coupling element 61 of a member 53 on one side and female-like coupling element 29 a counterpart thereof of a member 27 on the other side. A leading member 67 which is supported in such a manner as to be integrally rotated and moved in the direction of male-female interfit, always energized to the forward end side by an energizing means, and fittable in the female-like coupling element 29 so as to be conductible is provided on the forward end side from the male-like coupling element 61 of the member 53 on one side. When the leading member 67 is condactibly fitted to the female-like coupling element 29, the male-like coupling element 61 is male-female fitted to the inside of the female-like coupling element 29 by guiding of the leading member 67.