Well all medical devices on the European Market must be CE marked. So strictly speaking the answer to your question is typically "yes". However look on the box for the appropriate marking.
However I suspect you are probably asking how to find out whether an individual device is supported by a valid EC certificate?
The first thing to point out is that Class I devices (non-sterile, non-measuring) won't actually have a certificate...
Secondly, for a (e.g.) Class IIa device, this information is not actually deemed to be in the public domain. It is a private commercial arrangement between the manufacturer and the Notified Body. The Competent Authorities are involved only very peripherally.
Thus you will find that some companies hide their certification status, others broadcast it as far and as wide as they can.
If you write to a Notified Body asking whether a particular device is covered by appropriate certification, they may or may not respond, for the reasons described above.