An electron microscope having an electron beam irradiation portion for irradiating a sample with an electron beam, an electron detection device for detecting electrons emanating from the sample in response to the electron beam irradiation, and a sample carrier for transporting the sample into a position hit by the electron beam, said sample carrier comprising: a sample holder for holding the sample; a holder mounting member configured to be capable of being attached and detached to and from the sample holder and having a range of movement; and a transport portion for causing the holder mounting member to move rectilinearly; wherein said transport portion has a drive source, a rotary member rotated about its axis of rotation by the drive source, a guide portion for guiding the holder mounting member in a linear direction perpendicular to the axis of rotation of the rotary member, and a rod rotatably coupled to the rotary member and to the holder mounting member, the rod having a coupled portion coupled to the rotary member; wherein at a midpoint of the range of movement of the holder mounting member, the shortest distance from said coupled portion of the rod to said guide portion is greatest, said holder mounting member having a cylindrically shaped connective portion, a base portion fitted over the connective portion, and a biasing portion for biasing the connective portion toward the sample holder; wherein the connective portion has an outer peripheral portion on which an engagement piece is mounted, the connective portion being supported by the base portion so as to be rotatable about its axis and movable axially, one of the base portion and the connective portion having a cam groove, the other having cam pins that engage the cam groove; and wherein when the base portion moves relative to the connective portion axially of the connective portion, the cam pins and the cam groove cooperate to rotate the connective portion through a given angle in one rotational direction, whereby the engagement piece is placed either in an engagement position where the engagement piece engages the sample holder or a non-engagement position where the engagement piece disengages from the sample holder. a sample holder for holding the sample; a holder mounting member configured to be capable of being attached and detached to and from the sample holder and having a range of movement; and a transport portion for causing the holder mounting member to move rectilinearly; wherein said transport portion has a drive source, a rotary member rotated about its axis of rotation by the drive source, a guide portion for guiding the holder mounting member in a linear direction perpendicular to the axis of rotation of the rotary member, and a rod rotatably coupled to the rotary member and to the holder mounting member, the rod having a coupled portion coupled to the rotary member; wherein at a midpoint of the range of movement of the holder mounting member, the shortest distance from said coupled portion of the rod to said guide portion is greatest, said holder mounting member having a cylindrically shaped connective portion, a base portion fitted over the connective portion, and a biasing portion for biasing the connective portion toward the sample holder; wherein the connective portion has an outer peripheral portion on which an engagement piece is mounted, the connective portion being supported by the base portion so as to be rotatable about its axis and movable axially, one of the base portion and the connective portion having a cam groove, the other having cam pins that engage the cam groove; and wherein when the base portion moves relative to the connective portion axially of the connective portion, the cam pins and the cam groove cooperate to rotate the connective portion through a given angle in one rotational direction, whereby the engagement piece is placed either in an engagement position where the engagement piece engages the sample holder or a non-engagement position where the engagement piece disengages from the sample holder.