A medium transport device 4 includes a feeding section 7 having a first feed port 61 configured to feed a first medium 21 into the housing 5 at an upper section of a housing and a transport section 9 configured to transport the first medium in the transport direction F, wherein the feeding section includes a support section 13, which extends upward from the first feed port, and has a support surface 12 configured to support the first medium to be fed to the first feed port. a small width medium feeding section 27 configured to feed a second medium 22 having a smaller width dimension than the first medium 21, and the small width medium feeding section 27 is disposed at the first feed port 61 and includes a second feed port 28 configured to feed the second medium 22 into the housing and guide sections 31 and 32 configured to guide width direction edge sections 29 and 30 of the second medium.