Provided is an electric actuator, comprising: a driving motor (2); a motion conversion mechanism (6) configured to convert a rotary motion of the driving motor (2) to a linear motion in an axial direction parallel with an output shaft (2a) of the driving motor (2); and a transmission gear mechanism (5) configured to transmit a driving force from the driving motor (2) to the motion conversion mechanism (6), wherein a double-row bearing (24) configured to support the motion conversion mechanism (6) is arranged on an opposite side of the driving motor (2) with respect to the transmission gear mechanism (5), and wherein a relationship of L