The case came to light when the boy told his mother that he had smoked cannabis three times with their 35-year-old neighbour.
"The hash made him sick but he really liked the effect," according to the verdict in Sandefjord district court.
When quizzed by child welfare authorities the boy tried to protect his neighbour, saying he had found the hash himself. But the court ruled against the man, who was also charged with a string of other minor offences, including driving a quad bike under the influence.
The court sentenced him to 90 days in jail, with 60 days of the sentence suspended. He was also fined 8,000 kroner and ordered to pay court costs. He also had his driving licence revoked for 20 months.
The court said that even though the boy had only received very small quantities of the drug, this had happened several times and "in such a way that the boy did not receive instruction counteracting the use of narcotics."