In this paper, vibration acceleration was investigated at a power tiller handle position as well as seat position of a trailer pulled by the power tiller. The vibration acceleration signals were obtained in a field experiment using a 13-hp power tiller. The experiments were conducted at five levels of engine speed (1400, 1600, 1800, 2000 and 2200 rpm) and four levels of transmission gear ratio (2-light, 3-light, 2-heavy and 3-heavy) during transportation on an asphalt rural road. Three accelerometers were installed on the tractor handle and trailer seat positions on the lateral, longitudinal, and vertical directions. An analogue output of the accelerometers was converted to digital ones, using A/D converter with 40000 Hz sampling rate and stored in a laptop computer hard disk. The recorded digital signals were processed in time domain and then converted to frequency domain using a developed fast Fourier transform (FFT) program. The weighted 1/3rd octave spectrum was calculated from the narrow band vibration acceleration signals. The amount of vibration damage on operator\'s body and allowable exposure limits were calculated based on ISO standards. The results showed that the vibration acceleration increased with increasing the engine speed for all the gear ratios and directions at the both positions of handle and seat. The magnitude of vibration acceleration was the greatest at vertical direction in all the experiments. The vibration allowable exposure time was in the range of 2.32-5.7 years at the power tiller handle for the different engine speeds and gear ratios. As the results, the total equivalent vibration, A(8), at the trailer seat was in the range of 0.5 to 0.87 m/s2 and it exceeded the allowable limits for the reduced comfort boundary, fatigue-decreased boundary and exposure limit. Therefore, the exposure time should be lower than 8 hours/day. Finally, survey the results indicated that it is necessary to reduce the vibration transmitted to the operator’s hand and body by designing and developing adequate insulating systems.