An ear thermometer with a probe cover ejection device, comprising: a holding body; and a measuring assembly disposed at one end of the holding body, comprising: a probe; a rotating member including a ring cover with an opening formed in a middle of the ring cover, at least one first abutting portion axially extended from a lateral side of the ring cover, and a lever portion radially extended from the lateral side of the ring cover; and a socket including a circular bottom surface, a closed section and an open section defined on a periphery of the circular bottom surface, a side wall surface vertically provided on the closed section, an accommodating space sandwiched between the side wall surface and the circular bottom surface, and at least one second abutting portion formed on the circular bottom surface; wherein the rotating member is disposed in the accommodating space and the first abutting portion is pressed against the second abutting portion at a relatively slidable state, the lever portion is protruded at a position of the open section of the socket, and the probe passes through the opening and one end of the probe is fixed to the circular bottom surface of the socket; wherein the lever portion is configured to displace within the open section under force to let the first abutting portion move relative to the second abutting portion so that the whole rotating member synchronously rotates radially and moves axially to make a probe cover shelterable on the probe be radially and axially pushed and displaced simultaneously; wherein one of the first abutting portion and the second abutting portion is an inclined surface and has a valley (3121, 3224) and a peak (3122, 3225) oppositely disposed so that the one of the first abutting portion and the second abutting portion relatively abuts against the other of the first abutting portion and the second abutting portion at a position that moves from the valley (3121, 3224) to the peak (3122, 3225) when the lever portion is displaced in the open section. a holding body; and a measuring assembly disposed at one end of the holding body, comprising: a probe; a rotating member including a ring cover with an opening formed in a middle of the ring cover, at least one first abutting portion axially extended from a lateral side of the ring cover, and a lever portion radially extended from the lateral side of the ring cover; and a socket including a circular bottom surface, a closed section and an open section defined on a periphery of the circular bottom surface, a side wall surface vertically provided on the closed section, an accommodating space sandwiched between the side wall surface and the circular bottom surface, and at least one second abutting portion formed on the circular bottom surface; wherein the rotating member is disposed in the accommodating space and the first abutting portion is pressed against the second abutting portion at a relatively slidable state, the lever portion is protruded at a position of the open section of the socket, and the probe passes through the opening and one end of the probe is fixed to the circular bottom surface of the socket; a probe; a rotating member including a ring cover with an opening formed in a middle of the ring cover, at least one first abutting portion axially extended from a lateral side of the ring cover, and a lever portion radially extended from the lateral side of the ring cover; and a socket including a circular bottom surface, a closed section and an open section defined on a periphery of the circular bottom surface, a side wall surface vertically provided on the closed section, an accommodating space sandwiched between the side wall surface and the circular bottom surface, and at least one second abutting portion formed on the circular bottom surface; wherein the rotating member is disposed in the accommodating space and the first abutting portion is pressed against the second abutting portion at a relatively slidable state, the lever portion is protruded at a position of the open section of the socket, and the probe passes through the opening and one end of the probe is fixed to the circular bottom surface of the socket; wherein the lever portion is configured to displace within the open section under force to let the first abutting portion move relative to the second abutting portion so that the whole rotating member synchronously rotates radially and moves axially to make a probe cover shelterable on the probe be radially and axially pushed and displaced simultaneously; wherein one of the first abutting portion and the second abutting portion is an inclined surface and has a valley (3121, 3224) and a peak (3122, 3225) oppositely disposed so that the one of the first abutting portion and the second abutting portion relatively abuts against the other of the first abutting portion and the second abutting portion at a position that moves from the valley (3121, 3224) to the peak (3122, 3225) when the lever portion is displaced in the open section.