Tunnel magnetoresistance effect has been investigated for magnetic tunnel junctions with Co 2FeAl 0.5Si 0.5 Heusler electrodes on a Cr-bufferd MgO (110) substrate. The grown Co 2FeAl 0.5Si 0.5 has L2 1 structure for annealing above 500°C. The TMR ratio of 73 at room temperature and 103 at 5 K were obtained for a junction consists of MgO(110) substrate/Cr/Co 2FeAl 0.5Si 0.5/Al-oxide/Co 75Fe 25/IrMn/Ta. The tunnel magnetoresistance ratio obtained in this study is almost the same as that estimated by using magnetic tunnel junction with the same kind of Co 2FeAl 0.5Si 0.5 electrode on a Cr-bufferd MgO (001) substrate. Smaller temperature dependence of magnetoresistance ratio was also found for the junctions on Cr-bufferd MgO(110) substrates.