A field device, comprising: a sensor; a Δ∑ type analog-digital converter configured to perform a conversion process for converting detected signals output from the sensor and to continuously output converted digital signals; and a calculator configured to convert the digital signals to process values, wherein the calculator is configured to start acquisition of the digital signals output from the Δ∑ type analog-digital converter at a first point in time that is delayed by a processing time required for the conversion process of the Δ∑ type analog-digital converter from a start point of a timing signal defining a sampling section of the detected signals, and to finish the acquisition of the digital signals output from the Δ∑ type analog-digital converter at a second point in time that is delayed by the processing time from an end point of the timing signal; characterized in that the calculator comprises: a first counter configured to count a time from the start point to the end point of the timing signal; and a second counter configured to count the processing time; each of the first counter and the second counter is configured to start count at the start point of the timing signal, the first counter is configured to stop count at the end point of the timing signal, the second counter is configured to continue count at the end point of the timing signal, the calculator is configured to store a value (Cts) of the first counter at the end point of the timing signal, the second counter is configured to stop the count at the first point, the calculator is configured to acquire the digital signals, the number of which is equal to the value of the first counter, from the first point, the calculator is configured to count the number of the acquired digital signals whenever performing the acquisition of the digital signals, and the calculator is configured to finish the acquisition of the digital signals at the second point, wherein the second point equals to a time when the counted value (Cts) becomes the value of the first counter. a sensor; a Δ∑ type analog-digital converter configured to perform a conversion process for converting detected signals output from the sensor and to continuously output converted digital signals; and a calculator configured to convert the digital signals to process values, wherein the calculator is configured to start acquisition of the digital signals output from the Δ∑ type analog-digital converter at a first point in time that is delayed by a processing time required for the conversion process of the Δ∑ type analog-digital converter from a start point of a timing signal defining a sampling section of the detected signals, and to finish the acquisition of the digital signals output from the Δ∑ type analog-digital converter at a second point in time that is delayed by the processing time from an end point of the timing signal; characterized in that the calculator comprises: a first counter configured to count a time from the start point to the end point of the timing signal; and a second counter configured to count the processing time; each of the first counter and the second counter is configured to start count at the start point of the timing signal, the first counter is configured to stop count at the end point of the timing signal, the second counter is configured to continue count at the end point of the timing signal, the calculator is configured to store a value (Cts) of the first counter at the end point of the timing signal, the second counter is configured to stop the count at the first point, the calculator is configured to acquire the digital signals, the number of which is equal to the value of the first counter, from the first point, the calculator is configured to count the number of the acquired digital signals whenever performing the acquisition of the digital signals, and the calculator is configured to finish the acquisition of the digital signals at the second point, wherein the second point equals to a time when the counted value (Cts) becomes the value of the first counter. a first counter configured to count a time from the start point to the end point of the timing signal; and a second counter configured to count the processing time; each of the first counter and the second counter is configured to start count at the start point of the timing signal, the first counter is configured to stop count at the end point of the timing signal, the second counter is configured to continue count at the end point of the timing signal, the calculator is configured to store a value (Cts) of the first counter at the end point of the timing signal, the second counter is configured to stop the count at the first point, the calculator is configured to acquire the digital signals, the number of which is equal to the value of the first counter, from the first point, the calculator is configured to count the number of the acquired digital signals whenever performing the acquisition of the digital signals, and the calculator is configured to finish the acquisition of the digital signals at the second point, wherein the second point equals to a time when the counted value (Cts) becomes the value of the first counter.