Creep properties of the lamellar structured Ti-46.6Al-1.4Mn-2Mo(at%) alloy, which is made by hot extrusion of a blended elemental powder mixture, are investigated in air environment over the temperature range from 1023K to 1173K at constant stress levels ranging from 100MPa to 250MPa. The average activation energy for creep within the temperature range from 1048K∼1173K at stress level 150MPa and 200MPa is found to tie 384kJ/㏖. The value of the stress exponent n in the range of 3.8∼4.3 was obtained within the stress range from 150MPa to 250MPa and 1.3 between 100MPa and 150MPa at 1073K. Microstructural studies conducted on creep fractured specimen showed the secondary cracks along the lamellar grain boundaries and the secondary cracks are assumed to be formed by pore nucleation, growth and coalescence during the tertiary stage.