To provide a card conveyance mechanism for surely conveying a cracked or bent card without causing any conveyance jam.

This card conveyance mechanism includes: a conveyance path 30 configured of opposite conveyance guides 14 and 15; and conveyance rollers 11 and 12 arranged on the conveyance path 30 so as to face each other, and configured to convey a transaction card 50 by conveyance rollers 11 and 12 while holding both faces of the transaction card 50. The conveyance direction upstream side of a sensor detection hole 24 or a comb-like unit joint 38 formed in the conveyance guide 14 includes: a crack protrusion 54 of a card top end face 51 of a deformed card 50a to be conveyed, which protrudes to the conveyance guide 15 side; and conveyance support guides 20 and 70 for preventing the crack part 54a from being in contact with the sensor detection hole 24 or the unit joint 38.