David Armstrong, a supply teacher, escaped jail with a suspended sentence after admitting possessing 4,500 indecent images of children.
As she allowed the 63-year-old to walk free from court, Judge Mary Jane Mowat told him: I don't criticise you for being a teacher who's attracted to children.
Many teachers are but they keep their urges under control both when it comes to children and when it comes to images of children."
Child abuse campaigners yesterday described the comments as outrageous and an insult to victims.
Teachers also attacked the remarks, saying they cast a shadow over their profession and sent the wrong message to child sex offenders.
Peter Bradley, deputy director of the childrens charity Kidscape, said: Children who have been sexually abused would be horrified to read this judges remarks.
Schools are not places where those attracted to children can work schools are there to provide learning in a safe environment where children know the people who look after them can be trusted and relied upon.
This teacher should not have been in the profession and it is outrageous for the judge to say many teachers are sexually attracted to children.
The message needs to be clear if you are sexually attracted to children then you don't work with them.
Christine Blower, General Secretary of the National Union of Teachers, said: Teachers are professionals whose interest is ensuring children and young people achieve their educational potential.
To suggest their interest in pupils could understandably be anything else is totally unacceptable.
Jayne Phillips, Senior Legal Advocate at the Association of Teachers and Lecturers, added: It is a very worrying message to send out.
The judges comments do not reflect our knowledge of the UKs teaching staff they would be appalled by the suggestion that they are in anyway attracted to children.
Married Armstrong was caught after a colleague at the Little Heath School in Tilehurst, near Reading, Berks, reported him to police.
Reading Crown Court was told that the teaching assistant became alarmed after noticing files on Armstrongs laptop with names including rape wife, nude model and gay alligator,
Police arrested Armstrong and found 4,500 indecent images and videos on two laptops and an external hard drive. More than 300 of the images were in the two most serious categories, some involving children as young as two.
He admitted five charges of making indecent photographs or pseudo-photographs of children between 2007 and 2010. The court heard that some of the images were not of real children but Japanese cartoons depicting youngsters in sexual scenes.
Judge Mowat handed Armstrong a 12-month prison sentence, suspended for two years.
She added: This was by any standards a substantial collection, with some 300 of the worst kind.
Armstrong, of Devizes, Wilts, was placed on the Sex Offenders Register for ten years and served with a sexual prevention order banning him from owning a computer or device capable of connecting to the internet.
He was also ordered to undergo treatment for his attraction to children and is automatically banned from working with youngsters.
Robin Shellard, defending, said his client had worked at many schools and colleges during his career and had an impeccable record.
The case is not the first time Judge Mowat has stirred controversy over sentences handed to sexual offenders.
In 2008, she allowed former headmaster Phillip Carmichael to walk free from court after accepting that medication for Parkinsons disease had turned him into a paedophile.
Sentencing a bus driver to ten-months in jail in 2006 for abusing a 12-year-old girl, the judge acknowledged that she felt obliged to lock him up because of current views about sentences.
I have a record of trying to suspend sentences in cases like this and them ending up in the Court of Appeal, she told Robert Prout, following a public outcry over the brevity of prison sentences for sex offenders.
