In the central Paris area of Invalides, police said 141 people were arrested after violent incidents and clashes with security forces.
Sixty people were injured in the clashes nationwide, including 27 police officers
The violence was worst in the capital where a small group of masked rioters, who appeared to be separate from the main student-led march, threw stones and metal bars at firemen, smashed shop windows and lit cars on fire.
The Paris march drew 23,000 people and there were also violent rallies in other cities and towns including Marseille, Rennes, Grenoble and Lyon, as well as several Paris suburbs.
Altogether about 220,000 high school and university students took part in a fourth day of nationwide demonstrations against the government youth job reforms.
The First Employment Contract or CPE, passed earlier this month by the centre-right-led parliament, is an open-ended contract applicable for workers under 26 years of age that can be terminated within the first two years without justification.
Initially conceived by Prime Minister Dominique de Villepin as a tool against France's high youth unemployment rate, it is opposed by an alliance of students, unions and left-wing political parties, who see it as a breach in France's hard-won system of employee protection.