In order to reduce the smoke emission of PME/1-butanol blend by increasing the 1-butanol content, PME/1-butanol blend is tested using a DI diesel engine with jerk-type fuel injection pump. With PME/1-butanol blend, there is no problem on the start-ability and stability of the engine operation up to 60 mass% of 1-butanol. On the other hand, with gas oil/1-butanol blend, there is no problem on those up to 40 mass% of 1-butanol. The PME/1-butanol blend has longer ignition delay compared with PME due to the low cetane number of 1-butanol. With increasing 1-butanol content, the smoke emissions of PME/1-butanol blend decrease although the HC and CO emissions increase due to the longer ignition delay. From the experimental results, it is concluded that when considering the ignitability, the brake thermal efficiency and the exhaust emissions, the available maximum 1-butanol mixing ratio for PME/1-butanol blend is 50 mass%, which is 10 % higher than that for the gas oil/1-butanol blend, 40 mass%. Furthermore, to improve the ignitability of PME/1-butanol blend, by adding 1 mass% 2EHN to PME/1-butanol blend, the HC and CO emissions decrease due to the ignitability improvement and the available 1-butanol mixing ratio increases up to 60 mass% expect for low load condition.