The explosion occurred late on Saturday in Naushki town, some 200km southwest of the provincial capital Quetta.
Police said the bomb "was a low intensity homemade device", and was planted in a drain.
The man who died was a passerby. Fours cars were also damaged in the bombing.
No one claimed responsibility and no arrests were reported in connection with the explosion.
Saturday's explosion came a day after at least three soldiers were wounded when suspected tribesman fired some 12 rockets at their headquarters in Barakhan, a town about 370km east of Quetta.
Baluchistan has in recent months seen several small-scale bombings and rocket attacks targeting railways, security forces, gas pipelines and power lines.
The authorities blame renegade tribesmen - angered by government plans to build new military garrisons and demanding increased royalty payments for resources extracted from their territories - for the unrest in the impoverished region.