Magnetic one-component developing toner

A magnetic one-component developing toner comprising a plurality of toner particles, wherein

• each of the plurality of toner particles containing a binder resin and a magnetic powder,
• the binder resin including a polyester resin,
• where a mass of the toner measured after standing in a desiccator together with a desiccant in an environment of 25° C. for 48 hours is indicated as WTI, a mass of the toner, having been measured for the mass WTI, measured after standing in an environment of 10° C. and 20% RH for 48 hours is indicated as WTL, and a mass of the toner, having been measured for the mass WTI, measured after standing in an environment of 28° C. and 80% RH for 48 hours is indicated as WTH, a water absorption ATL of the toner obtained in accordance with the following formula (1) is 0.07% by mass or less:
• ATL=((WTL−WTI)/WTI)×100 (1) and
• a water absorption ATH of the toner obtained in accordance with the following formula (2) is 0.27% by mass or more and 0.34% by mass or less:
• ATH=((WTH−WTI)/WTI)×100 (2), and
• where a mass of the magnetic powder measured after standing in a desiccator together with a desiccant in an environment of 25° C. for 48 hours is indicated as WMI, that a mass of the magnetic powder, having been measured for the mass WMI, measured after standing in an environment of 10° C. and 20% RH for 48 hours is indicated as WML, and a mass of the magnetic powder, having been measured for the mass WMI, measured after standing in an environment of 28° C. and 80% RH for 48 hours is indicated as WMH, a water absorption AML of the magnetic powder obtained in accordance with the following formula (3) is 0.08% by mass or more:
• AML=((WML−WMI)/WMI)×100 (3), and
• a water absorption AMH of the magnetic powder obtained in accordance with the following formula (4) is 0.25% by mass or less:
• AMH=((WMH−WMI)/WM1)×100 (4)