An interlayer film for laminated glass, having a one-layer structure or a two or more-layer structure and containing a thermoplastic resin, the thermoplastic resin containing a polyvinyl butyral resin, wherein a portion on a first surface of the interlayer film is measured for Ratio 0 of Ion Intensity of Magnesium/Ion Intensity of Thermoplastic Resin with the use of TOF-SIMS, and a sputtering and measurement process in which the first surface portion measured for Ratio 0 is subjected to sputtering one time and measured for Ratio of Ion Intensity of Magnesium/Ion Intensity of Thermoplastic Resin with the use of TOF-SIMS is performed n times, and n Ratio n s of Ion Intensity of Magnesium/Ion Intensity of Thermoplastic Resin obtained from the first to n-th sputtering and measurement processes are collected to calculate an average value 1 ≤ n ≤ 10 of 10 values of Ratio 1 ≤ n ≤ 10 measured within a range of 1 ≤ n ≤ 10, an average value 11 ≤ n ≤ 20 of 10 values of Ratio 11 ≤ n ≤ 20 measured within a range of 11 ≤ n ≤ 20, an average value 21 ≤ n ≤ 30 of 10 values of Ratio 21 ≤ n ≤ 30 measured within a range of 21 ≤ n ≤ 30, an average value 31 ≤ n ≤ 40 of 10 values of Ratio 31 ≤ n ≤ 40 measured within a range of 31 ≤ n ≤ 40, and an average value 41 ≤ n ≤ 50 of 10 values of Ratio 41 ≤ n ≤ 50 measured within a range of 41 ≤ n ≤ 50, the Ion Intensities of Magnesium and Ion Intensities of Thermoplastic Resin each being measured according to the method in the description, among these five average values, the average value indicating the smallest value is the average value 1 ≤ n ≤ 10 or the average value 11 ≤ n ≤ 20 and the average value indicating the largest value is the average value 21 ≤ n ≤ 30, the average value 31 ≤ n ≤ 40, or the average value 41 ≤ n ≤ 50, and wherein, in the case of an interlayer film with the one-layer structure, the content of magnesium in the interlayer film is 200 ppm or less and the content of potassium in the interlayer film is 100 ppm or less, and in the case of an interlayer film with the two or more-layer structure, the content of magnesium in a surface layer positioned at the first surface side is 200 ppm or less, and the content of potassium in the surface layer positioned at the first surface side is 100 ppm or less. containing a thermoplastic resin, the thermoplastic resin containing a polyvinyl butyral resin, wherein a portion on a first surface of the interlayer film is measured for Ratio 0 of Ion Intensity of Magnesium/Ion Intensity of Thermoplastic Resin with the use of TOF-SIMS, and a sputtering and measurement process in which the first surface portion measured for Ratio 0 is subjected to sputtering one time and measured for Ratio of Ion Intensity of Magnesium/Ion Intensity of Thermoplastic Resin with the use of TOF-SIMS is performed n times, and n Ratio n s of Ion Intensity of Magnesium/Ion Intensity of Thermoplastic Resin obtained from the first to n-th sputtering and measurement processes are collected to calculate an average value 1 ≤ n ≤ 10 of 10 values of Ratio 1 ≤ n ≤ 10 measured within a range of 1 ≤ n ≤ 10, an average value 11 ≤ n ≤ 20 of 10 values of Ratio 11 ≤ n ≤ 20 measured within a range of 11 ≤ n ≤ 20, an average value 21 ≤ n ≤ 30 of 10 values of Ratio 21 ≤ n ≤ 30 measured within a range of 21 ≤ n ≤ 30, an average value 31 ≤ n ≤ 40 of 10 values of Ratio 31 ≤ n ≤ 40 measured within a range of 31 ≤ n ≤ 40, and an average value 41 ≤ n ≤ 50 of 10 values of Ratio 41 ≤ n ≤ 50 measured within a range of 41 ≤ n ≤ 50, the Ion Intensities of Magnesium and Ion Intensities of Thermoplastic Resin each being measured according to the method in the description, among these five average values, the average value indicating the smallest value is the average value 1 ≤ n ≤ 10 or the average value 11 ≤ n ≤ 20 and the average value indicating the largest value is the average value 21 ≤ n ≤ 30, the average value 31 ≤ n ≤ 40, or the average value 41 ≤ n ≤ 50, and wherein, in the case of an interlayer film with the one-layer structure, the content of magnesium in the interlayer film is 200 ppm or less and the content of potassium in the interlayer film is 100 ppm or less, and in the case of an interlayer film with the two or more-layer structure, the content of magnesium in a surface layer positioned at the first surface side is 200 ppm or less, and the content of potassium in the surface layer positioned at the first surface side is 100 ppm or less.