A bed includes a sliding unit movable on a base and a linkage unit including a following element, a board, a connecting rod, a swinging element and a hydraulic cylinder. The following element is connected to the sliding unit. The board is connected to the following element so that they are rotatable together to and from the sliding unit. The connecting rod includes an end connected to the sliding unit. The swinging element includes an end connected to the connecting rod and another end connected to a head crossbar of the base. The hydraulic cylinder includes a pivotal end connected to the base and an extensible end connected to the swinging element. Thus, the swinging element can be pivoted upwards to actuate the connecting rod to move the sliding unit toward the head crossbar and actuate the connecting rod to push the board.
