CAMBRIDGE, Mass. (AP) _ A ''very respectable'' man was held on $1 million bond today on charges he bilked 12 people out of a total of $19,000 by offering to rent them a house he didn't own or represent, police say.

Robert Lane, 30, is accused of renting a house in suburban Newton under an alias and running advertisements listing a telephone number that was answered in the name of a nonexistent real estate firm.

The four-bedroom, two-bathroom house was advertised at $1,000 a month.

Lane was charged with stealing $19,000 from the bilked tenants, who handed over payments averaging $2,000, authorities said. The would-be tenants included several groups of roommates.

James Katz, of Waltham, said he answered the ad and found the man he dealt with ''very believable, he looked and acted real square.''

Newton Detective Sgt. Arthur Fryar, who arrested Lane last month, said, ''The guy is an absolute professional, he had actual leases. You'd never question him, he looked very reputable, very respectable.''

Lane was indicted last week by a Middlesex County grand jury on 12 charges of larceny over $100 and two charges of using false identification.

Court documents say Lane called himself Daniel J. Murphy and told people who thought they were renting the house to make out checks to Merton Perlstick. Police say that was another false name under which Lane held bank accounts.

When arrested, Lane was on parole for assault and battery conviction, authorities said.

Judge Hiller Zobel set the high bail on Monday in Middlesex Superior Court after Lane, acting as his own attorney, pleaded innocent. Jeffrey Locke, an assistant district attorney, said he sought the bail because Lane skipped out on $1,000 bail set after an unrelated 1983 arrest.