For biometric technologies, a sensing device and a terminal device are provided. The sensing device includes a circuit board, a biometric sensor, at least one light-emitting element, a cover with a light-transmitting region, a light guide plate, and a light concentrating structure. The biometric sensor is installed on the circuit board. The light guide plate is fixed between the biometric sensor and the cover. The light concentrating structure is disposed on the light guide plate and corresponds to the light-transmitting region. The light-emitting element is installed on the circuit board and positioned on one side of the biometric sensor; and the light-emitting element has a side light-emitting end, and the side light-emitting end corresponds to the light guide plate.