To provide a hinge mechanism capable of folding or developing two plate members in a predetermined order with excellent operability.

The two-axis hinge mechanism comprises fitting mechanism 512 and 32 which are fitted to each other to prevent a plate member 11 from being further relatively turned in the folding direction to a hinge member 5 when the imaginary line L orthogonal to the axes of both shaft parts 3 and 4 is substantially orthogonal to a surface of the plate member 11, and release the fitting when the force exceeding a predetermined value to turn the plate member 11 in the developing direction is applied to the hinge member 5, and fitting mechanisms 525 and 42 which are fitted to each other to prevent a plate member 12 from being further turned in the developing direction with respect to the hinge member 5 when the imaginary line L is substantially parallel to the surface of the plate member 12, and release the fitting when the force exceeding the predetermined value to turn the plate member 12 in the folding direction is applied to the hinge member 5.