A card reader having a magnetic head which abuts on a card to read magnetic information recorded on said card and/or write magnetic information on said card and mounted in a host device for use, comprising: an anterior frame in which an insertion slot for said card is formed, wherein said anterior frame is provided with a front face portion configuring the anterior of said card reader; a main body frame fixed to said anterior frame; a control board to which said magnetic head is electrically connected; and a sealing member which is formed to be annular and is arranged between said anterior frame and said main body frame; wherein, having the insertion direction of said card as a first direction, said main body frame is provided with a head arrangement in which said magnetic head is arranged, a sac-like card cage in which said first direction side of said card inserted from said insertion slot is housed, and a seal arrangement which is formed between said head arrangement and said card cage and in which said sealing member is positioned such that the inner circumference of said sealing member makes contact therewith; characterized in that said anterior frame is provided with a substantially cylindrical cylinder portion which is formed to connect to said front face portion and formed from said front face portion toward said first direction; said head arrangement is positioned on the inner circumferential side of said cylinder portion; said insertion slot is formed to said front face portion such that said card inserted from said insertion slot passes on the inner circumferential side of said cylinder portion; said first direction end side portion of said cylinder portion is formed as a seal crushing portion that crushes said sealing member in the radial direction from the outer circumferential side of said sealing member; said control board is arranged more toward said first direction side than said seal arrangement and also outside said card cage; and the inner circumferential face of said seal crushing portion is formed in a tapered shape fanning out in the radial direction of said seal crushing portion as toward said first direction. an anterior frame in which an insertion slot for said card is formed, wherein said anterior frame is provided with a front face portion configuring the anterior of said card reader; a main body frame fixed to said anterior frame; a control board to which said magnetic head is electrically connected; and a sealing member which is formed to be annular and is arranged between said anterior frame and said main body frame; wherein, having the insertion direction of said card as a first direction, said main body frame is provided with a head arrangement in which said magnetic head is arranged, a sac-like card cage in which said first direction side of said card inserted from said insertion slot is housed, and a seal arrangement which is formed between said head arrangement and said card cage and in which said sealing member is positioned such that the inner circumference of said sealing member makes contact therewith; characterized in that said anterior frame is provided with a substantially cylindrical cylinder portion which is formed to connect to said front face portion and formed from said front face portion toward said first direction; said head arrangement is positioned on the inner circumferential side of said cylinder portion; said insertion slot is formed to said front face portion such that said card inserted from said insertion slot passes on the inner circumferential side of said cylinder portion; said first direction end side portion of said cylinder portion is formed as a seal crushing portion that crushes said sealing member in the radial direction from the outer circumferential side of said sealing member; said control board is arranged more toward said first direction side than said seal arrangement and also outside said card cage; and the inner circumferential face of said seal crushing portion is formed in a tapered shape fanning out in the radial direction of said seal crushing portion as toward said first direction.