Abstract: A single-acting type hydraulic cylinder which is operated to be expanded and contracted by supply and discharge of liquid pressure from a so-called bottom side, in which the desired operation is permanently secured without bringing forth abrasion of a bushing or damage of a dust seal caused by rust or scratching in the outer circumference of a rod body. A hydraulic cylinder which is operated to be expanded and contracted by supply and discharge of liquid pressure P to a liquid chamber R partitioned on the bottom side within a cylinder body 1, characterized in that a head member 4 forming an open end of the cylinder body 1 is provided with a lubrication means 7 in sliding contact with the outer circumference of a rod body 3 and an oil seal 8 in series between a bushing 5 and a dust seal 6.