Failsafe hydraulic circuit

A failsafe hydraulic circuit designed to avoid simultaneous engagement of two friction engagement elements (e.g., clutches, brakes, etc.) incorporated in a speed change apparatus of a motor vehicle or the like. If a first failsafe valve is in the open position state and a first engaging pressure is supplied to a first hydraulic servo via the first failsafe valve, the first engaging pressure is also input to a first oil pressure switch via a second failsafe valve being in the closed position state. Therefore, using the first oil pressure switch, it can be detected that the first engaging pressure is supplied to the first hydraulic servo. Furthermore, if the first engaging pressure is, for example, greater than the set pressure of the first oil pressure switch, this situation can also be detected. Such detections provide confirmation of normal operation of the first failsafe valve and the second failsafe valve.