A power transmission apparatus (20, 120) comprising: an input shaft inputted with a power, an output shaft for outputting the power, a clutch device (23, 123) operative to be changed to selectively take a disconnected state in which the power is disconnected between the input shaft and the output shaft or a connected state in which the power is connected between the input shaft and the output shaft, and an actuator for driving the clutch device (23, 123), the clutch device (23, 123) comprising an input side rotation element integrally rotated with the input shaft, an output side rotation element integrally rotated with the output shaft, an engagement element pack constituted by a plurality of input side friction engagement elements integrally rotated with the input side rotation element and a plurality of output side friction engagement elements integrally rotated with the output side rotation element, an input side cam mechanism that presses the engagement element pack toward the output shaft, an urging element that urges the engagement element pack to have the input side friction engagement elements and the output side friction engagement elements axially moved away from each other, characterized by further comprising: an output side cam mechanism (35, 35A, 135) that presses the engagement element pack toward the input shaft, and a drive shaft (37, 137) having an input side transmission element (37n, 137n) that transmits a driving force outputted from the actuator to the input side cam mechanism, and an output side transmission element (37d, 137d) that transmits the driving force to the output side cam mechanism (35, 35A, 135), the input side cam mechanism and the output side cam mechanism (35, 35A, 135) being driven by the rotation of the drive shaft (37, 137). an input shaft inputted with a power, an output shaft for outputting the power, a clutch device (23, 123) operative to be changed to selectively take a disconnected state in which the power is disconnected between the input shaft and the output shaft or a connected state in which the power is connected between the input shaft and the output shaft, and an actuator for driving the clutch device (23, 123), the clutch device (23, 123) comprising an input side rotation element integrally rotated with the input shaft, an output side rotation element integrally rotated with the output shaft, an engagement element pack constituted by a plurality of input side friction engagement elements integrally rotated with the input side rotation element and a plurality of output side friction engagement elements integrally rotated with the output side rotation element, an input side cam mechanism that presses the engagement element pack toward the output shaft, an urging element that urges the engagement element pack to have the input side friction engagement elements and the output side friction engagement elements axially moved away from each other, characterized by further comprising: an output side cam mechanism (35, 35A, 135) that presses the engagement element pack toward the input shaft, and a drive shaft (37, 137) having an input side transmission element (37n, 137n) that transmits a driving force outputted from the actuator to the input side cam mechanism, and an output side transmission element (37d, 137d) that transmits the driving force to the output side cam mechanism (35, 35A, 135), the input side cam mechanism and the output side cam mechanism (35, 35A, 135) being driven by the rotation of the drive shaft (37, 137). an output side cam mechanism (35, 35A, 135) that presses the engagement element pack toward the input shaft, and a drive shaft (37, 137) having an input side transmission element (37n, 137n) that transmits a driving force outputted from the actuator to the input side cam mechanism, and an output side transmission element (37d, 137d) that transmits the driving force to the output side cam mechanism (35, 35A, 135), the input side cam mechanism and the output side cam mechanism (35, 35A, 135) being driven by the rotation of the drive shaft (37, 137).