The invention provides a portable terminal device of the foldable type wherein a manipulation-side cabinet and a display-side cabinet each comprises a front cabinet segment and a rear cabinet segment joined thereto. The manipulation-side cabinet has its front cabinet segment connected at an end portion thereof to a hinge mechanism and has its rear cabinet segment engaged with the front cabinet segment thereof. The display-side cabinet has its rear cabinet segment connected at an end portion thereof to the hinge mechanism and has its front cabinet segment engaged with the rear cabinet segment thereof.