A teller cash recycler, comprising: a handling unit including a bill receiving unit, a bill dispensing unit (140, 141), a main conveyance unit, a discrimination device and at least one switching gate (190, 191, 192); a safe provided under the handling unit and configured to provide a space for storing bills; a cassette mounting part provided outside the safe; a removable cassette selectively mounted to the cassette mounting part to supplement bills to the safe or collect the bills stored in the safe; a control unit configured to control an operation of the teller cash recycler; a plurality of cassettes provided inside the safe and configured to store bills, wherein the plurality of cassettes include a plurality of first cassettes (210a, 210b, 210c) having a first size, and a plurality of second cassettes (220a, 220b, 220c) having a second size smaller than the first size, and wherein the first cassettes (210a, 210b, 210c) are disposed at an upper side in the safe in a spaced-apart relationship in a front-rear direction, and the second cassettes (220a, 220b, 220c) are disposed at a lower side in the safe in a spaced-apart relationship in the front-rear direction; at least one vertical conveyance unit (240a, 240b) having an upper end connected to the main conveyance unit and a lower end connected to the second cassettes (220a, 220b, 220c); and a plurality of interfaces (150, 151, 152, 153, 154, 155) configured to provide conveyance routes between the handling unit and the safe, the interface (150, 151, 152, 153, 154, 155) having an upper end connected to the main conveyance unit and a lower end extending downward from the handling unit and inserted into the safe, wherein the bills stored in the removable cassette are conveyed between the handling unit and the second cassette (220a, 220b, 220c) through the interface (150, 153) and said at least one vertical conveyance unit (240a, 240b) and wherein the teller cash recycler is configured to store bills having a relatively high use frequency in the first cassettes (210a, 210b, 210c) and to store bills having a relatively low use frequency in the second cassettes (220a, 220b, 220c). a handling unit including a bill receiving unit, a bill dispensing unit (140, 141), a main conveyance unit, a discrimination device and at least one switching gate (190, 191, 192); a safe provided under the handling unit and configured to provide a space for storing bills; a cassette mounting part provided outside the safe; a removable cassette selectively mounted to the cassette mounting part to supplement bills to the safe or collect the bills stored in the safe; a control unit configured to control an operation of the teller cash recycler; a plurality of cassettes provided inside the safe and configured to store bills, wherein the plurality of cassettes include a plurality of first cassettes (210a, 210b, 210c) having a first size, and a plurality of second cassettes (220a, 220b, 220c) having a second size smaller than the first size, and wherein the first cassettes (210a, 210b, 210c) are disposed at an upper side in the safe in a spaced-apart relationship in a front-rear direction, and the second cassettes (220a, 220b, 220c) are disposed at a lower side in the safe in a spaced-apart relationship in the front-rear direction; at least one vertical conveyance unit (240a, 240b) having an upper end connected to the main conveyance unit and a lower end connected to the second cassettes (220a, 220b, 220c); and a plurality of interfaces (150, 151, 152, 153, 154, 155) configured to provide conveyance routes between the handling unit and the safe, the interface (150, 151, 152, 153, 154, 155) having an upper end connected to the main conveyance unit and a lower end extending downward from the handling unit and inserted into the safe, wherein the bills stored in the removable cassette are conveyed between the handling unit and the second cassette (220a, 220b, 220c) through the interface (150, 153) and said at least one vertical conveyance unit (240a, 240b) and wherein the teller cash recycler is configured to store bills having a relatively high use frequency in the first cassettes (210a, 210b, 210c) and to store bills having a relatively low use frequency in the second cassettes (220a, 220b, 220c).