extension of student visa application

i am doing phd in japan. my stay is going to expire in mid october. I apply for extension and waiting for application acceptance since one month. it usually takes three weeks. i am worried. is it sign of rejection?
can any one tell me what is maximum time usually.

wow ,, im waiting my COE to go there in October ,,, you make me worried man ,, i hope you will get the extension,, let us know what happened .

my stay is going to expire in mid october. I apply for extension and waiting for application acceptance since one month.

So you applied in mid-July? Was that directly with immigration (as you're supposed to apply within 2 months of the expiration date, not 3), or did you go through an intermediary such as your school. If it is through the school then they may be holding on to it still, as the earliest time to submit will be around now.

i submitted application by my self at imigration office after getting some necessary document from school. Lady at imigration office told me that it will take 3 weeks but 5th week is passing.