The 1986–87 Segunda División season saw 18 teams participate in the second flight Spanish league.

Champions of promotion groups (Valencia CF and Celta de Vigo) and the best second placed team (CD Logroñés) were promoted to Primera División.

The last three in the relegation group should have been relegated at the end of the season, but in the middle of the season it was decided that Primera División and Segunda División would be expanded to 20 teams.

Finally, there were no relegations to Segunda División B.

Since Primera and Segunda División would be expanded to 20 teams, no teams were relegated to Segunda División B.