David Farnon, 22, of St Wilfrid’s Close, who admitted the offence, was stopped by police while driving his Volkswagen Polo on the A16 at Stickford on March 19.
He admitted to police he had been smoking cannabis and a blood analysis showed a reading of 5.6 micrograms in his blood, the legal limit being two.
Matthew Tye, mitigating, said Farnon fully admitted his responsibility and had cooperated with the police.
He said Farnon had started smoking cannabis at the suggestion of a friend to cope with grief when his grandmother died.
He was banned from driving for 12 months and ordered to pay a fine of £120 and a total of £119 in court costs and charges.