A safety valve system (20A;20B) comprising: a main valve that has an introduction port into which pressure from a pressure source is to be introduced, a release port which is configured to release the pressure, a dome chamber, and a valve body arranged such that the introduction port and the release port are cut off from each other in a closed state of the valve body and are communicated with each other in an open state of the valve body, wherein the valve body is further arranged to be opened and closed in accordance with a pressure difference between the introduction port and the release port, and wherein the valve body is configured to be brought into the closed state when the pressure of the dome chamber and the pressure of the introduction port is equal to each other; a high-pressure side pilot valve that is set to a first operating pressure value and that is configured to release the pressure by allowing the introduction port and the release port to communicate with each other by opening the valve body when the pressure exceeds the first operating pressure value; a low-pressure side pilot valve that is set to a second operating pressure value lower than the first operating pressure value and that is configured to release the pressure by allowing the introduction port and the release port to communicate with each other by opening the valve body when the pressure exceeds the second operating pressure value; a first pressure introduction line that connects the high-pressure side pilot valve to the dome chamber; a first return line that connects the pressure source to the high-pressure side pilot valve, a second pressure introduction line that connects the low-pressure side pilot valve to the dome chamber; a second return line that connects the pressure source to the low-pressure side pilot valve, and a switching unit (24A;24B) that is configured to perform switching between non-operation and operation of the low-pressure side pilot valve, characterized in that the switching unit (24A;24B) includes a first opening-closing valve (27;127) provided at the second pressure introduction line and a second opening-closing valve (28;128) provided at the second return line, and wherein the switching unit (24A;24B) is configured to perform switching between operation and non-operation of the low-pressure side pilot valve by opening and closing the first opening-closing valve (27;127) and the second opening-closing valve (28;128). a main valve that has an introduction port into which pressure from a pressure source is to be introduced, a release port which is configured to release the pressure, a dome chamber, and a valve body arranged such that the introduction port and the release port are cut off from each other in a closed state of the valve body and are communicated with each other in an open state of the valve body, wherein the valve body is further arranged to be opened and closed in accordance with a pressure difference between the introduction port and the release port, and wherein the valve body is configured to be brought into the closed state when the pressure of the dome chamber and the pressure of the introduction port is equal to each other; a high-pressure side pilot valve that is set to a first operating pressure value and that is configured to release the pressure by allowing the introduction port and the release port to communicate with each other by opening the valve body when the pressure exceeds the first operating pressure value; a low-pressure side pilot valve that is set to a second operating pressure value lower than the first operating pressure value and that is configured to release the pressure by allowing the introduction port and the release port to communicate with each other by opening the valve body when the pressure exceeds the second operating pressure value; a first pressure introduction line that connects the high-pressure side pilot valve to the dome chamber; a first return line that connects the pressure source to the high-pressure side pilot valve, a second pressure introduction line that connects the low-pressure side pilot valve to the dome chamber; a second return line that connects the pressure source to the low-pressure side pilot valve, and a switching unit (24A;24B) that is configured to perform switching between non-operation and operation of the low-pressure side pilot valve, characterized in that the switching unit (24A;24B) includes a first opening-closing valve (27;127) provided at the second pressure introduction line and a second opening-closing valve (28;128) provided at the second return line, and wherein the switching unit (24A;24B) is configured to perform switching between operation and non-operation of the low-pressure side pilot valve by opening and closing the first opening-closing valve (27;127) and the second opening-closing valve (28;128).