It is an object of the present invention to improve seal performance in an electric linear motion actuator configured to linearly drive a linear motion member due to the rotation of a rotary shaft. The linear motion member is constituted by a cylindrical member slidably fitted in a housing, and a pressing member coupled to the distal end portion of the cylindrical member so as to close the opening of the distal end of the cylindrical member. The portion of the pressing member coupled to the cylindrical member is located inside of a boot sealing the space between the distal end portion of the housing and the distal end portion of the linear motion member.