An accumulator comprising: a tank provided with an inflow port and an outflow port; an outflow pipe having a double pipe structure including an inner pipe connected to the outflow port so as to be dropped inside the tank and an outer pipe disposed on the outer periphery of the inner pipe; and a strainer provided in a vicinity of a lower end of the outflow pipe, the strainer including a casing, and a mesh filter, wherein the mesh filter is attached to the casing such that it is disposed between a space formed between the inner pipe and the outer pipe, and a space inside the inner pipe, wherein the accumulator further includes a communication hole (46; 46') that is provided in the casing of the strainer, wherein said communication hole causes the space formed between the inner pipe and the outer pipe to communicate with a lower space of the tank, wherein the mesh filter, the casing of the strainer and the communication hole are arranged such that oil flows sequentially from the communication hole (46; 46') to the mesh filter and to the inner pipe, wherein the casing of the strainer includes a cylindrical body portion to which an outer end of the mesh filter is connected and a bottom plate portion which is provided in a lower end of the body portion and has a diameter larger than the body portion, wherein a lower end of the inner pipe is connected to an upper portion of the body portion and a lower end of the outer pipe is connected to an outer periphery of the bottom plate portion, and wherein the communication hole is formed between the outer pipe and the body portion in the bottom plate portion. a tank provided with an inflow port and an outflow port; an outflow pipe having a double pipe structure including an inner pipe connected to the outflow port so as to be dropped inside the tank and an outer pipe disposed on the outer periphery of the inner pipe; and a strainer provided in a vicinity of a lower end of the outflow pipe, the strainer including a casing, and a mesh filter, wherein the mesh filter is attached to the casing such that it is disposed between a space formed between the inner pipe and the outer pipe, and a space inside the inner pipe, wherein the accumulator further includes a communication hole (46; 46') that is provided in the casing of the strainer, wherein said communication hole causes the space formed between the inner pipe and the outer pipe to communicate with a lower space of the tank, wherein the mesh filter, the casing of the strainer and the communication hole are arranged such that oil flows sequentially from the communication hole (46; 46') to the mesh filter and to the inner pipe, wherein the casing of the strainer includes a cylindrical body portion to which an outer end of the mesh filter is connected and a bottom plate portion which is provided in a lower end of the body portion and has a diameter larger than the body portion, wherein a lower end of the inner pipe is connected to an upper portion of the body portion and a lower end of the outer pipe is connected to an outer periphery of the bottom plate portion, and wherein the communication hole is formed between the outer pipe and the body portion in the bottom plate portion.