With figures such as Pete Doherty and Prince Harry admitting to having used illegal substances, primary school children need the facts, according to David Bell.
A report to be published by Ofsted, the education standards watchdog, on Thursday will reveal that a growing number of primary schools are giving anti-drugs lessons to seven- and eight-year-olds.
Mr Bell, who is also chief executive of Ofsted, told The Independent on Sunday: "If you went to primary schools in most parts of the country, you would find children from seven to eight upwards have an understanding of drugs. They hear about popstars taking drugs.
"It reinforces the idea that schools must take it seriously."
He added that he could "confidently" predict that more primary schools would be giving priority to tackling the subject in the future.
"I'm afraid I tend to be a hardliner on this," Mr Bell said. "Teachers must point out the dangers of illicit drugs."
Thursday's report, the first look at drugs education by inspectors for eight years, will also reveal that pupils are demanding to be taught more about the dangers of binge-drinking and tobacco use.
They believe they both pose a bigger threat to them than illicit drugs.
"We are recognising that there is concern about drinking, and more schools will emphasise that it's not smart to drink too much," Mr Bell said.
The survey of anti-drugs lessons in 60 schools will also reveal that most are rejecting the idea of using random drugs tests or sniffer dogs to detect their presence.
Mr Bell said many schools were worried these methods might draw attention to drugs and exacerbate any problems.
"The majority won't go down that route," he said. "After all, most young people say they don't indulge.
"In schools that use these methods, most will say this wasn't a decision taken lightly. I'd support any head who decides to use random tests."
The survey reveals that more schools have now devised their own drugs policies - which range from "zero tolerance" of drug use to a more sympathetic stance for the one-off user of a drug.
Mr Bell said: "We can be quite encouraged by the progress schools have made in making sure that youngsters know about drugs and the risks associated with them."