Is it common for Thai immigration to retain a passport when applying for a student visa?

Governments frequently hold passports.

Yes that's OK..I had mine held for a day ..just ask for a reciet that they hold it

Yes, it is common for Thai immigration or the Ministry of Education to keep a passport for several days when processing a student visa or an extension of stay. This is standard procedure, as they need to verify your documents, process your application, and affix the appropriate visa or extension stamp.

However, if you are applying through an agent or a school, you should ensure they are trustworthy before handing over your passport. If you’re dealing directly with immigration, it is generally safe, but you can ask for a receipt or any official acknowledgment that they have your passport.

If you’re uncomfortable, you might inquire about alternative procedures, such as submitting a certified copy instead of the original passport until the final step.

Immigration doesn't keep your passport

It's the immigration office It's as save as can be

Common

I would take a picture of passport and the entry stamp prior to handing it over to immigration. Especially if you're going to be out in public.

It happenes. Getting a non b in Laos, they keep your passport foe 2 days 😵 nerve recking but it's part of the process. If you are doing it through your agency they keep it for a few days to save you the hassle of traveling with them everywhere. It's difficult but trust. They don't have I'll intentions

Very normal in Thailand

Quite legal for an immigration office to hold on to your passport and give you it back the next afternoon with the visa in it as done it in Phuket many times ,agency's are another question as I would never trust some of them ,heard too much horror stories

Immifration or an agent has your passport?

Sounds like you're using an agency and not applying to immigration yourself. There's only one immigration office I know of that sometimes holds passports, and that's only overnight and you pick up the next day. But agents will hold your passport for longer. If you're willing to risk that is up to you. It has happened in the past that agents will say they're taking care of everything and give stories and hold the passports for months, and then ultimately you'll find out they never did anything except take your money and you've been on overstay all that time. It's rare but it happens. There's always a risk if you're not doing everything yourself the correct and legal way.