To provide a slip suppressing control device for steel wheel system moving body and a slip suppressing control method of steel wheel system moving body, which can recover the driving force in the earlier period after a re-adhesion, by reducing the level of the slip suppression, when a minute slip is continued.

When the ratio T2/T1 of the total sum value T2 in a minute slip time which is the time that a speed difference VS in the time turning back to the past as a specific object time T1 from the time to detect the slip, is a minute slip time of a driving wheel 7 is made more than the first speed difference VS1, to the specific object time T1, is more than a specific time ratio TA, a main line controller driving force instruction MC is changed to the second control driving force instruction NC2=MC-GC where the main line controller driving force instruction MC is reduced as a reduction driving force instruction GC reducing the value of a return driving force instruction FC, so as to control the output of a diesel engine 4, to suppress the minute slip of a driving wheel 7.