It can take anywhere from a few hours to 3 days (max). It depends on when and where you deposit the cheque and whether the issuer and depositor are with the same bank.
If you deposit in the morning (before 11am, I believe) through a teller or a cheque deposit machine, it should clear on the same day. If you deposit the cheque into an ATM (in an envelope), it can take longer because they have to come and empty the machine to collect it.
If the cheque still hasn't cleared after 3 days, then there is a problem (signature mismatch, insufficient funds, etc.) and you need to contact the bank to find out what the problem is and where to collect the cheque from (normally bank HQ).