Pee's when we leave the room

Hi everyone
i have a 10 month old male golden retriever we got him about 1 month ago, he's great and training is going very well. the only problem and this is a major one is if we are in the room with him and then we step outside the room and close the door so he can't follow us. such as when we go to the toilet or get something from the master bedroom where he is not allowed.
he will pee on the floor about one min after we leave. its not alot of pee but still its trouble having to wipe it up 1-3 times ever day

any advice would be great
thanks

when potty training watch your dog at ALL times. if you cant watch him put him in the crate, or even on a leash and take him with you into the master bedroom. i know he is not allowed but if he is leashed onto you what can he hurt?

success to potty traning is simlpy dont leave your dog alone. dont give him a chance to potty in the house.