An impact tool which transmits an impact force to a tool bit supported by a tool body, comprising: a cylinder member which is attached to the tool body and has an opening on one end side thereof to which the tool bit is inserted; a regulation member which is provided inside the cylinder member and comprising a projection; an impact force transmitting member which is provided in an inside of the cylinder member so as to be able to move straight, has a projection projecting in a radial direction so as to regulate a range of the straight movement, and transmits the impact force to the tool bit; wherein in an inside of the tool body, a driving force transmitting mechanism (25,29,30,38,63) which is lubricated with a lubricant, and a storage chamber in which the driving force transmitting mechanism (25,29,30,38,63) is stored and with which an opening on the other end side of the cylinder member is communicated are provided, the outside of the cylinder member is connected with the storage chamber, characterised in that the impact tool comprises a passage (70,71) which communicates the inside of the cylinder member at a position nearer to the tool bit than the projection of the impact force transmitting member in a direction of the straight movement of the impact force transmitting member with an outside of the cylinder member in a state where the tool bit is pressed against a machining object to move the impact force transmitting member and the projection of the impact force transmitting member comes into contact with the projection of the regulation member, so that the impact force transmitting member stops, and penetrates through the cylinder member in a radial direction, and in that the impact tool further comprises a sealing device which inhibits the lubricant from leaking from the opening on the one end side of the cylinder member is provided at a position nearer to the tool bit than the projection of the impact force transmitting member in a direction of the straight movement of the impact force transmitting member. a cylinder member which is attached to the tool body and has an opening on one end side thereof to which the tool bit is inserted; a regulation member which is provided inside the cylinder member and comprising a projection; an impact force transmitting member which is provided in an inside of the cylinder member so as to be able to move straight, has a projection projecting in a radial direction so as to regulate a range of the straight movement, and transmits the impact force to the tool bit; wherein in an inside of the tool body, a driving force transmitting mechanism (25,29,30,38,63) which is lubricated with a lubricant, and a storage chamber in which the driving force transmitting mechanism (25,29,30,38,63) is stored and with which an opening on the other end side of the cylinder member is communicated are provided, the outside of the cylinder member is connected with the storage chamber, characterised in that the impact tool comprises a passage (70,71) which communicates the inside of the cylinder member at a position nearer to the tool bit than the projection of the impact force transmitting member in a direction of the straight movement of the impact force transmitting member with an outside of the cylinder member in a state where the tool bit is pressed against a machining object to move the impact force transmitting member and the projection of the impact force transmitting member comes into contact with the projection of the regulation member, so that the impact force transmitting member stops, and penetrates through the cylinder member in a radial direction, and in that the impact tool further comprises a sealing device which inhibits the lubricant from leaking from the opening on the one end side of the cylinder member is provided at a position nearer to the tool bit than the projection of the impact force transmitting member in a direction of the straight movement of the impact force transmitting member.