An operator cab for heavy equipment is described to prevent a sliding door mounted on the cab from rocking or rattling in X, Y, and Z-axis directions due to a shock or vibration applied to the cab in a state that the sliding door is fully opened. The operator cab includes an outer sidewall having a doorway formed thereon; upper and lower rails provided on upper and lower portions of the outer sidewall and engaged with upper and lower rollers; a sliding door being slid by upper and lower rollers engaged with the upper and lower rails; an upper pad formed on an upper bracket; a lower pad formed on a lower bracket; an upper stopper, installed in the opened position of the outer sidewall, for being in surface contact with the upper pad when the sliding door is fully opened, and preventing the sliding door from rocking when the upper stopper becomes in surface contact with the upper pad; and a lower stopper, installed in the opened position of the outer sidewall, for being in surface contact with the lower pad when the sliding door is fully opened, and preventing the sliding door from rocking when the lower stopper becomes in surface contact with the lower pad.