A sputum apparatus comprising: a suction line having a suction inlet being capable of aspirating sputum produced in a patient's respiratory tract, and an accommodating part to accommodate the aspirated sputum, the accommodating part being maintained at a negative pressure; and a switching unit being capable of switching between a first state and a second state, the first state making the suction inlet communicate with the accommodating part, the second state making the suction inlet shut off from the accommodating part, the switching unit being placed in the suction line; and a control unit, characterized in that the sputum apparatus further includes a measurement unit to measure an expired air being aspirated into the accommodating part, under the first state, and a detection unit capable of detecting respiratory status of the patient, wherein the control unit determines expiration phase of the patient, based on an output of the detection unit, wherein the control unit is capable of switching the switching unit from the second state to the first state during expiration phase of the patient, and capable of keeping the switching unit to the first state when an amount of the expired air measured by the measurement unit is less than a predetermined value. a suction line having a suction inlet being capable of aspirating sputum produced in a patient's respiratory tract, and an accommodating part to accommodate the aspirated sputum, the accommodating part being maintained at a negative pressure; and a suction inlet being capable of aspirating sputum produced in a patient's respiratory tract, and an accommodating part to accommodate the aspirated sputum, the accommodating part being maintained at a negative pressure; and a switching unit being capable of switching between a first state and a second state, the first state making the suction inlet communicate with the accommodating part, the second state making the suction inlet shut off from the accommodating part, the switching unit being placed in the suction line; and a control unit, characterized in that the sputum apparatus further includes the first state making the suction inlet communicate with the accommodating part, the second state making the suction inlet shut off from the accommodating part, the switching unit being placed in the suction line; and a control unit, characterized in that the sputum apparatus further includes a measurement unit to measure an expired air being aspirated into the accommodating part, under the first state, and a detection unit capable of detecting respiratory status of the patient, wherein the control unit determines expiration phase of the patient, based on an output of the detection unit, wherein the control unit is capable of switching the switching unit from the second state to the first state during expiration phase of the patient, and capable of keeping the switching unit to the first state when an amount of the expired air measured by the measurement unit is less than a predetermined value. capable of switching the switching unit from the second state to the first state during expiration phase of the patient, and capable of keeping the switching unit to the first state when an amount of the expired air measured by the measurement unit is less than a predetermined value.