A structured combustion chamber for an engine has a cylinder head with an intake hole portion communicating between an intake port and a combustion chamber and an exhaust hole portion which makes a communication between an exhaust port and the combustion chamber, an intake valve for opening and closing the intake hole portion, and a continuous variable valve lift mechanism for lifting the intake valve in a stepless fashion, a flow promoting device is provided to promote a motion of an air current in the combustion chamber when a quantity of lift of the intake valve driven by the continuous variable valve lift mechanism is small and further to suppress a decrease in flow rate of an intake air coming through the intake hole portion into the combustion chamber when the quantity of lift of the intake valve driven by the continuous variable valve lift mechanism reaches a maximum.