Maybe. And maybe not.
Most safes require you to enter your own password to both open and close the safe. One traveler forgot his password and asked the front desk for help. Turns out the default password provided by manufacturers is all zeroes and this particular hotel did not change it. (http://www.gadling.com/2011/09/06/your-hotel-room-safe-not-as-safe-as-you-think/?ncid=webmail9)
The take-away: Before leaving valuables in your room’s safe, check to see if the all zeroes is the default password. If so, skip the room safe and tuck your valuables away in the hotel’s own safe adjacent to the front desk.
Although your Better Business Bureau does not condone this, some travelers prefer to hide items in plain sight 9http://www.gadling.com/2010/03/29/hiding-valuables-in-your-hotel-room/) – a passport tucked in with useless papers, items squirreled away in an opaque shampoo bottle, even an envelope taped to the bottom of a trash bucket.
Perhaps the best solution is to not travel with valuables, but if you must, take them with you wherever you go.
How do you keep valuables safe while traveling?