The men's 400 metres hurdles at the 2007 World Championships in Athletics was held at the Nagai Stadium on 25, 26 and 28 August.

Prior to the competition, the following records were as follows.

Qualification: First 4 in each heat (Q) and the next 4 fastest (q) advance to the semifinals.

Qualification: First 2 in each semifinal (Q) and the next 2 fastest (q) advance to the final.