The Tory leader says people value plumbers more than lawyers, but the school system does not recognise this.
Michael Howard - a barrister by profession - said one cause of truancy was that academic qualifications were valued more than practical skills.
Speaking at a city academy in Nottingham, he said he wanted everyone to make a success of their life.
Labour and the Liberal Democrats both also have their own proposals aimed at boosting vocational learning.
Mr Howard said that around the country he had seen children who had dropped out of school.
"One the tragedies of our education system is that we have overvalued the importance of an academic qualification at the expense of a technical or practical skill," he said.
"I believe this is one of the root causes of truancy.
"If youngsters who know they are never going to make it to university cannot learn a practical skill, should we be surprised when they get angry and frustrated with an inflexible academic curriculum which seems only to highlight their failings?"
It was, he said, "time to end that snobbery".
Further education should no longer be "the forgotten garden of the education world".
"Ask anyone whom they would value most: a good lawyer or a good plumber?
"And I can tell you - as a lawyer - what their answer would be. And it's not my profession."
The way to build esteem for such professions was to raise the quality and standard of education.
"Then everyone knows that a young person who has chosen a vocational route, and come out of it with flying colours, is talented, skilled and proficient."
So a Conservative government would establish a network of "skills super colleges".
Funding would come from the abolition of Learning and Skills Councils.
Children aged 14 and 15 would be able to start on a vocational path from school with colleges providing specialist courses for them.
The party intends to provide £1,000 grants to encourage them to do this.
The Liberal Democrats say they would establish a "climbing frame of learning" in which pupils could mix academic and skills-based courses, and replace GCSE, A-level and vocational qualifications with a new diploma system.
They would seek to close the funding gap between schools and colleges - colleges say they get at least 10% less.
Labour decided not to adopt this approach, which had been advocated by its own Tomlinson inquiry into 14 to 19 learning.
It plans new diplomas just for vocational skills, designed in collaboration with employers, plus "skills academies", and is encouraging children from 14 to take college courses.