The present disclosure provides a method and apparatus for sequentially detecting and decoding multiuser sparse code multiple access (SCMA) signal. A detection method includes selecting a single variable node depending on how much the plurality of variable nodes each use function nodes that connect to updated variable nodes; updating messages passed to the single variable node, based on a function node input message passed to the plurality of function nodes and signals received by the plurality of function nodes through channels; mapping updated messages to a priori information of a channel decoder; inputting the priori information to the channel decoder and thereby obtaining probability information of a symbol for the single variable node; and updating messages passed from the single variable node to one of the plurality of function nodes by applying a weight to the probability information of the symbol for the single variable node.