Suspension apparatus

1. A suspension apparatus comprising:

a cylindrical outer tube;

an inner tube which is coaxially arranged inside the outer tube to move in an axial direction relative to the outer tube and into which oil is poured;

a piston which is inserted into the inner tube;

a piston rod of which one end portion retains the piston and which moves together with the outer tube with respect to the inner tube; and

a partition wall member that is mounted to an upper end portion of the inner tube to define an upper end portion of an annular oil chamber which is formed between an inner circumferential surface of the outer tube and an outer circumferential surface of the inner tube, that has a bowl portion formed into a bowl shape located inside the inner tube, and that divides a space inside the inner tube into an inner space and an outer space of the bowl portion, said inner space including an oil-containing inner space,

wherein a cross-sectional area of the annular oil chamber is larger than a cross-sectional area of the piston rod,

the partition wall member divides the outer space into a gap space between the partition wall member and the inner tube and a space other than the gap space,

a through-hole is formed in the partition wall member to communicate the oil-containing inner space with the gap space,

at least one of the partition wall member and the inner tube is provided with a communication path through which an upper portion of the annular oil chamber communicates with the gap space, and

the communication path has an inward concave portion that is concave inward from a side surface of the bowl portion of the partition wall member, said inward concave portion being helically formed in the side surface of the bowl portion.