To provide a cover opening/closing apparatus which is miniaturized.

The cover opening/closing apparatus comprises a shaft part having a rotary shaft, an arm part connected to a cover and the rotary shaft, and an actuator 60 to drive the rotary shaft. The actuator 60 comprises a motor 61 having an output portion 61a, a first reducer 62 having an input portion 62a and an output portion 62b, and a second reducer 63 having an input portion 63a and an output portion 63b. The reciprocal of the reduction ratio of the second reducer 63 is larger than the quotient of the product of the difference between the maximum value of the torque applied to the output portion 63b when the cover is opened and the torque required to rotate the output portion 63b when no torque is applied to the input portion 63a, with the ratio of the remainder of the torque after being subjected to a mechanical loss by the second reducer 63 out of the torque applied to the output portion 63b to the torque applied to the output portion 63b.