A valve open/close timing control device, comprising: a driving rotating body that rotates synchronously with a driving shaft of an internal combustion engine; a driven rotating body that is arranged inside of the driving rotating body, coaxially with an axis of the driving rotating body, and rotates integrally with a camshaft for opening/closing a valve of the internal combustion engine; a fluid pressure chamber defined between the driving rotating body and the driven rotating body; an intermediate lock mechanism capable of, with supply/discharge of a working fluid, selectively switching between a locked state in which a relative rotation phase of the driven rotating body with respect to the driving rotating body is constrained to an intermediate lock phase between a maximum advance phase and a maximum retard phase, and an unlocked state in which the constraint to the intermediate lock phase is released; an unlocking channel that allows passage of the working fluid to be supplied to or discharged from the intermediate lock mechanism; characterized in that it also comprises: a lock discharge channel that does not allow passage of the working fluid to be supplied to the intermediate lock mechanism, but allows passage of the working fluid discharged from the intermediate lock mechanism to the outside; and an electromagnetic valve that is disposed inside of the driven rotating body, coaxially with the axis, and controls the supply and discharge of the working fluid to/from the fluid pressure chamber and the intermediate lock mechanism by changing an electricity supply amount, wherein if the electricity supply amount to the electromagnetic valve is 0 or the maximum, the lock discharge channel allows the passage of the working fluid such that the working fluid is discharged to the outside. a driving rotating body that rotates synchronously with a driving shaft of an internal combustion engine; a driven rotating body that is arranged inside of the driving rotating body, coaxially with an axis of the driving rotating body, and rotates integrally with a camshaft for opening/closing a valve of the internal combustion engine; a fluid pressure chamber defined between the driving rotating body and the driven rotating body; an intermediate lock mechanism capable of, with supply/discharge of a working fluid, selectively switching between a locked state in which a relative rotation phase of the driven rotating body with respect to the driving rotating body is constrained to an intermediate lock phase between a maximum advance phase and a maximum retard phase, and an unlocked state in which the constraint to the intermediate lock phase is released; an unlocking channel that allows passage of the working fluid to be supplied to or discharged from the intermediate lock mechanism; characterized in that it also comprises: a lock discharge channel that does not allow passage of the working fluid to be supplied to the intermediate lock mechanism, but allows passage of the working fluid discharged from the intermediate lock mechanism to the outside; and an electromagnetic valve that is disposed inside of the driven rotating body, coaxially with the axis, and controls the supply and discharge of the working fluid to/from the fluid pressure chamber and the intermediate lock mechanism by changing an electricity supply amount, wherein if the electricity supply amount to the electromagnetic valve is 0 or the maximum, the lock discharge channel allows the passage of the working fluid such that the working fluid is discharged to the outside. a lock discharge channel that does not allow passage of the working fluid to be supplied to the intermediate lock mechanism, but allows passage of the working fluid discharged from the intermediate lock mechanism to the outside; and an electromagnetic valve that is disposed inside of the driven rotating body, coaxially with the axis, and controls the supply and discharge of the working fluid to/from the fluid pressure chamber and the intermediate lock mechanism by changing an electricity supply amount, wherein if the electricity supply amount to the electromagnetic valve is 0 or the maximum, the lock discharge channel allows the passage of the working fluid such that the working fluid is discharged to the outside.