A motor transmission unit for an electronic parking brake device includes a case, a driving member, a board, a rod and a push unit. The case is slidably mounted to a cap of a clamp. The driving member is partially inserted into the case. The board is threadedly mounted to the driving member. The rod is located between inner periphery of the passage and the board. The push unit has a first end thereof contacting the first end face, and a second end of the push unit is inserted in the clamp. A portion of the second end of the push unit contacts a piston. When the driving member is driven, the board moves axially. The board is restricted by the rod and does not rotate. The board pushes the push unit axially which moves the piston to push a lining plate of the clamp to contact a brake disk.