Families set up chairs near the court in memory of the deceased
Judges found Juan Pio Paiva guilty of manslaughter, but rejected calls for a harsher sentence over the 2004 blaze.
His son Daniel was jailed for 10 years and security guard Daniel Areco for five over the fire which injured 400.
Relatives have accused Mr Paiva of blocking people's escape by locking the stores' doors to prevent looting.
The first trial on the fire, held in 2006, was annulled by the Supreme Court after thousands of people rioted, believing the original verdict to be too lenient.
Lacking safety features
But families of the victims have complained that the new prison terms are still too lenient.
Hundreds of people protested outside the court calling for the defendants to be given the maximum sentence of 25 years.
Three shareholders were acquitted.
Several hundred people were inside when the fire broke out
The fire began in a chimney that an investigation found had been badly built and badly maintained.
The shop was also found to have lacked an effective fire detection system or proper emergency exits.
The defendants were charged with negligent homicide and endangering people in the workplace.
The court blamed them for chaining shut the doors of the Ycua Bolanos store in Asuncion after the fire had started.
During the trial the defendants said they had closed down the supermarket because they feared those inside would start looting, AFP news agency reported.
It was the worst fire in Paraguayan history.
A court in Paraguay has completed its trial over the worst fire disaster the country has ever seen. The Ycuá Bolaños supermarket fire in Asunción left 374 dead, 450 others injured and nine missing, presumed dead.

Store owner Juan Pio Paiva, 64, received 12 years imprisonment whilst his son Daniel Paiva, 40, was given 10 years. A security guard, Daniel Areco, was given a five-year sentence while three business associates of the Paivas were cleared of any criminal activity.

2,000 people were in the store when fire broke out on August 1, 2004, including many families with young children. Fire doors were shut to prevent looting, worsening the situation.

The investigation found that flames broke out in a badly built chimney because of inadequately maintained equipment. A lack of fire escapes, fire detection system and fire suppression system all contributed to the disaster. Most of the deaths were caused by asphyxiation due to the smoke. The nine missing bodies are believed to have been completely destroyed by the extreme temperature.

Paiva senior was convicted on the basis that as the owner and chief administrator of the business, including the building, he was responsible for overall safety. His son was responsible for the food court area, the site where the blaze started. The security guard was convicted for blocking the exits, although he was acting on senior orders. The three other businessmen were acquitted as they were not involved in the administration of the store.

The Paivas were both convicted of manslaughter and exposing people to danger within the workplace. Areco was found guilty of negligence.

The three judge tribunal was headed by German Torres. It replaced an earlier trial in 2006, when the court announced that it was 2-1 in favour of more lenient sentences, but got no further as friends and relatives stormed the courtroom and rioted in the streets outside. The court had been going to hand out five-year sentences to the Paivas.

A peaceful protest was also held at yesterday's verdict, with demonstrators shouting "Assassins! Assassins!" and "This kind of justice is injustice!" Ten women who lost relatives fainted in the heat and were hospitalised. The protestors were pressing for those involved to receive the maximum possible sentence of 25 years. One, Lys Torres, vowed to use the appeals courts to press for tougher sentences. "Its an outrage. They're responsible for the death of 400 people and they've been given ridiculous sentences," said Lys, who is a spokeswoman for the relatives and survivors group. "This shows that in this country, people with money can kill with impunity," Bersabe Meza, who lost her husband in the fire, said.

Chief prosecuter Edgar Sanchez, who had also requested maximum sentences, said "My conscience is clear. I've done my job."Meanwhile, relatives laid out a white plastic chair in the streets for each of those killed, adorned with signs bearing such notices as "If there is no justice, the people will rise up."

The ruined store remains standing, graffitied and adorned in tribute to those who died.