Insulated state detection device

An insulated state detection device includes a positive-side input terminal, a negative-side input terminal, a ground electrode, a ground fault resistance value calculation unit, a measuring state identification unit, a timing information generation unit that generates a timing information, automatically updates a value of the timing information by a predetermined value each time the ground fault resistance value calculation unit generates a new insulation resistance value, and reflects a state of the identification of the measuring state identification unit on the value of the timing information, and an information transmission unit that transmits the insulation resistance value calculated by the ground fault resistance value calculation unit and the timing information generated by the timing information generation unit to a host control device.