The officer, who was wearing a protective suit, was attempting to open the front passenger door of the parked car when the bomb exploded.
Authorities arrived at the scene after receiving a tip-off about the abandoned car, which was left in a no-parking zone.
The bomb disposal expert despite being lawn away nearly 10-meters by the explosion, picked himself up and walked away. He was treated for minor injuries.
Authorities said the bomb was triggered by remote from someone near the scene.
No group has claimed responsibility for the attacks so far, but the incident was believed to be linked to Muslim militants.
There has been a recent increase in the number and scale of attacks with Muslim villagers, soldiers and police among the victims of roadside blasts and ambushes.
About 4,600 people have been killed and nearly 9,000 wounded in violence since 2004.
Ethnic Malay Muslims, represent the majority of the population in the southernmost provinces of predominantly Buddhist Thailand, have long complained of discrimination, especially in education and job opportunities.
