A toilet apparatus comprising: a main part including a function part, and a case cover covering the function part, the main part being attached on a toilet bowl; and a toilet seat attached rotatably to the case cover, the toilet seat shifting between a closed state and an open state, in the closed state a user being capable of seating upward the toilet bowl, in the open state an upper surface of the toilet bowl being exposed, the case cover including an extending portion, a height of the extending portion becoming low toward forward, and a toilet seat pivot support portion provided backward the extending portion, and pivotally supporting the toilet seat, the toilet seat including a first portion positioned forward the case cover in the closed state, and a second portion rising backward from the first portion in the closed state, overlapping the extending portion, and being pivotally supported to the toilet seat pivot support portion, and an upper end surface of the toilet seat pivot support portion changing to lower a height toward forward, and forming a generally continuous surface to an upper end surface of the second portion, and wherein the toilet apparatus further comprises: a height change of a forefront of the upper end surface of the toilet seat pivot support portion in a horizontal direction is generally the same as a height change of a rear end of the upper end surface of the second portion in the horizontal direction, and characterised in that in a cross-section orthogonal to a forward-backward direction, a height of a center portion of the upper end surface of the toilet seat pivot support portion is higher than a height of a side end portion of the upper end surface of the toilet seat pivot support portion, and in that in the cross-section orthogonal to the forward-backward direction, the height of a center portion of the upper end surface of the second portion is lower than a height of a side end portion of the upper surface end of the second portion. a main part including a function part, and a case cover covering the function part, the main part being attached on a toilet bowl; and a toilet seat attached rotatably to the case cover, the toilet seat shifting between a closed state and an open state, in the closed state a user being capable of seating upward the toilet bowl, in the open state an upper surface of the toilet bowl being exposed, the case cover including an extending portion, a height of the extending portion becoming low toward forward, and a toilet seat pivot support portion provided backward the extending portion, and pivotally supporting the toilet seat, an extending portion, a height of the extending portion becoming low toward forward, and a toilet seat pivot support portion provided backward the extending portion, and pivotally supporting the toilet seat, the toilet seat including a first portion positioned forward the case cover in the closed state, and a second portion rising backward from the first portion in the closed state, overlapping the extending portion, and being pivotally supported to the toilet seat pivot support portion, and a first portion positioned forward the case cover in the closed state, and a second portion rising backward from the first portion in the closed state, overlapping the extending portion, and being pivotally supported to the toilet seat pivot support portion, and an upper end surface of the toilet seat pivot support portion changing to lower a height toward forward, and forming a generally continuous surface to an upper end surface of the second portion, and wherein the toilet apparatus further comprises: a height change of a forefront of the upper end surface of the toilet seat pivot support portion in a horizontal direction is generally the same as a height change of a rear end of the upper end surface of the second portion in the horizontal direction, and characterised in that in a cross-section orthogonal to a forward-backward direction, a height of a center portion of the upper end surface of the toilet seat pivot support portion is higher than a height of a side end portion of the upper end surface of the toilet seat pivot support portion, and in that in the cross-section orthogonal to the forward-backward direction, the height of a center portion of the upper end surface of the second portion is lower than a height of a side end portion of the upper surface end of the second portion. a height change of a forefront of the upper end surface of the toilet seat pivot support portion in a horizontal direction is generally the same as a height change of a rear end of the upper end surface of the second portion in the horizontal direction, and characterised in that in a cross-section orthogonal to a forward-backward direction, a height of a center portion of the upper end surface of the toilet seat pivot support portion is higher than a height of a side end portion of the upper end surface of the toilet seat pivot support portion, and in that in the cross-section orthogonal to the forward-backward direction, the height of a center portion of the upper end surface of the second portion is lower than a height of a side end portion of the upper surface end of the second portion.