Creep tests of the (001)[110] iron single crystals were done in the temperature range from 600°C to 880°C under normal stress from 0.5 to 2.5 kg/mm². Creep behaviour of the single crystal was essentially the same as that of polycrystalline iron at a stress larger than 0.7 kg/mm²; grain boundary has a minor role in the present experimental condition. Subgrains were formed during creep as in the case of molybdenum single crystals. Many screw dislocations were observed within subgrains. Subgrain size was almost inversely proportional to creep stress and the dislocation density within subgrains was proportional to creep stress, while both of them were independent of creep temperature.