And when Mr. Cardenas emerged from the voting booth on election day, he announced that he had cast his own presidential ballot for Super Barrio, which sent the masked man's stock rising even further. Super Barrio has since returned the favor by appearing at mass rallies in which Mr. Cardenas presses his claim that widespread fraud in the elections deprived him of victory.

On one level, Super Barrio is an effort to blend comic book heros such as Spiderman, Superman and Zorro with a Mexican tradition of wrestlers who go into the ring disguised and are invincible so long as they are not unmasked. As Super Barrio himself explained his origins: ''One day when I was in my room, I was enveloped in a brilliant red and yellow light, and when it dissipated, I was dressed this way. Then a voice said to me, 'You are Super Barrio, defender of tenants and scourge of greedy landlords.' ''

But in a broader social context, both Super Barrio and the movement he has come to symbolize are really outgrowths of the earthquake that devastated this city in September 1985. Many houses and apartment buildings were destroyed, thousands of people were made homeless, and real estate speculation on a scale not seen before began. His First Appearance

In neighborhoods around the capital, families forced to live in the streets or with relatives banded together informally to press the Government for rapid reconstruction of new homes. In April 1987, after the bulk of the reconstruction was over, the groups united formally as the Assembly of Barrios to lobby for expansion of Government housing, utility and sewer programs, and not long afterward Super Barrio made his first public appearance.

''The reconstruction of the city is an achievement that has improved the lives of many people,'' Mr. Saucedo said. ''Our reasoning was that if this much could be done, why not continue?''

As his fame has reached national proportions, Super Barrio has been invited to appear at events as diverse as university conferences in Puebla and antinuclear demonstrations in Vera Cruz. Locally, he is also broadening the scope of his activities to include issues such as police corruption, pollution and transportation.

''Today, my struggle is not only against landlords but against all those who commit injustices with the support of power or a Government post,'' Super Barrio said. 'We Are All Super Barrio'