Sabu, hailing from nearby Kundara, was just coming out of the Munciff Court room and was in the building veranda when a few particles of the explosion hit him, police said.
"It is a low intensity Improvised Explosive Device (IED)', Thiruvananthapuram IG Manoj Abraham said.
"The IED with electronic circuit is of low intensity. It is not damaging, but the presence of electronic circuit is very significant," IG Manoj Abraham said.
Further investigation into the incident was on, he said.
More From This Section
A holiday was declared for the court in the wake of the blast.
Sabu, who has come to the court in connection with a case, later told reporters that he heard a loud sound and some particles struck his eyes.
"I was just coming out of the Munciff Court room when I heard the sound. It started bleeding and my shirt was soaked with blood," he said.
The IED was planted beneath the parked vehicle, which was partially damaged under the impact of the blast, police said.
The explosion caused a scare among the litigant and others who gathered at the spot.
Police also recovered gelatin sticks and 17 batteries and fuse materials from the jeep.