To provide a variable compression ratio device for an internal combustion engine that can reduce frequency of starting failure of the internal combustion device, the failure being caused by movement failure of either a variable valve gear or a variable compression mechanism.

The variable compression ratio device 2 includes: the variable valve gear 20 for changing a valve timing of a suction valve 21; the variable compression mechanism 60; and a phase locking mechanism for locking the valve timing to an intermediate angle, which is away from a maximum delay angle toward a phase advancing side.