The medical bag 1 includes a bag main body 2 constituted by a flexible sheet material 21 having an interior portion partitioned via a partition part 5 into a first space 3 and a second space 4, and a first liquid 30 housed in the first space 3 and a second liquid 40 housed in the second space 4 ； the partition part 5 has been obtained by sandwiching the sheet material 21 by an upper mold 81 disposed on a higher side in the vertical direction than the sheet material and having a surface temperature of 130 to 145°C, and a lower mold 82 disposed on a lower side in the vertical direction than the sheet material 21 and having a surface temperature being 20 to 30°C lower than the surface temperature of the upper mold 81, and melt-bonding the sheet material 21 by the upper and lower molds； and the medical bag 1 has been obtained by sterilizing at 118 to 125°C for 20 to 45 minutes. The ratio L1/L2 of the volume L1 of the first liquid 30 to the volume L2 of the second liquid 40 is 2.0 to 6.0, and the partition part 5 has a breaking strength of 5 to 25 kPa.
