A medical equipment comprising: an optical connector that detachably connects a plug to a receptacle provided in an equipment main body to optically connect a first, plug-side optical fiber fixed to the plug and a second, receptacle-side optical fiber fixed to the receptacle, wherein the plug includes a plug-side holder that maintains the first optical fiber, the receptacle includes a receptacle-side holder that holds the second optical fiber, and a holder alignment unit that elastically supports the receptacle-side holder in an insertion direction (a) of the plug and supports the receptacle-side holder so that the receptacle-side holder is movable in a direction perpendicular to the insertion direction, a plurality of engagement pairs (145, 137; 149, 151), each consisting of a protrusion and an engagement part, wherein the protrusion (151, 145) of each engagement pair is formed in one of the plug and the receptacle, and protrudes in the insertion direction (a) of the plug, the engagement part (149, 137) of each engagement pair is formed in the other of the plug and the receptacle, and is adapted to be engaged with the corresponding protrusion, characterized in that engagement beginning positions of the engagement pairs where the protrusions and the engagement parts begin to engage are different along the insertion direction of the plug, and each engagement pair (145, 137; 149, 151) has a gap between its protrusion and its engagement part in the direction perpendicular to said insertion direction (a), wherein (i) any engagement pair the protrusion and the engagement part of which begin to engage earlier has a wider gap, and (ii) any engagement pair the protrusion and the engagement part of which begin to engage later has a narrower gap. an optical connector that detachably connects a plug to a receptacle provided in an equipment main body to optically connect a first, plug-side optical fiber fixed to the plug and a second, receptacle-side optical fiber fixed to the receptacle, wherein the plug includes a plug-side holder that maintains the first optical fiber, the receptacle includes a receptacle-side holder that holds the second optical fiber, and a holder alignment unit that elastically supports the receptacle-side holder in an insertion direction (a) of the plug and supports the receptacle-side holder so that the receptacle-side holder is movable in a direction perpendicular to the insertion direction, a plurality of engagement pairs (145, 137; 149, 151), each consisting of a protrusion and an engagement part, wherein the protrusion (151, 145) of each engagement pair is formed in one of the plug and the receptacle, and protrudes in the insertion direction (a) of the plug, the engagement part (149, 137) of each engagement pair is formed in the other of the plug and the receptacle, and is adapted to be engaged with the corresponding protrusion, characterized in that engagement beginning positions of the engagement pairs where the protrusions and the engagement parts begin to engage are different along the insertion direction of the plug, and each engagement pair (145, 137; 149, 151) has a gap between its protrusion and its engagement part in the direction perpendicular to said insertion direction (a), wherein (i) any engagement pair the protrusion and the engagement part of which begin to engage earlier has a wider gap, and (ii) any engagement pair the protrusion and the engagement part of which begin to engage later has a narrower gap. (i) any engagement pair the protrusion and the engagement part of which begin to engage earlier has a wider gap, and (ii) any engagement pair the protrusion and the engagement part of which begin to engage later has a narrower gap.